diff --git a/clientcompat/gocompat/gocompat.go b/clientcompat/gocompat/gocompat.go
index 044fe125..c84938a6 100644
--- a/clientcompat/gocompat/gocompat.go
+++ b/clientcompat/gocompat/gocompat.go
@@ -15,7 +15,7 @@ package main
 
 import (
 	"context"
-	"io/ioutil"
+	"io"
 	"log"
 	"net/http"
 	"os"
@@ -28,7 +28,7 @@ import (
 
 func main() {
 	var in clientcompat.ClientCompatMessage
-	inBytes, err := ioutil.ReadAll(os.Stdin)
+	inBytes, err := io.ReadAll(os.Stdin)
 	if err != nil {
 		log.Fatalf("read stdin err: %v", err)
 	}
diff --git a/clientcompat/internal/clientcompat/clientcompat.pb.go b/clientcompat/internal/clientcompat/clientcompat.pb.go
index 62aa7edb..83e40e20 100644
--- a/clientcompat/internal/clientcompat/clientcompat.pb.go
+++ b/clientcompat/internal/clientcompat/clientcompat.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: clientcompat.proto
 
diff --git a/clientcompat/internal/clientcompat/clientcompat.twirp.go b/clientcompat/internal/clientcompat/clientcompat.twirp.go
index 1dcfb7c4..c60f78cd 100644
--- a/clientcompat/internal/clientcompat/clientcompat.twirp.go
+++ b/clientcompat/internal/clientcompat/clientcompat.twirp.go
@@ -6,7 +6,7 @@ package clientcompat
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewCompatServiceProtobufClient(baseURL string, client HTTPClient, opts ...t
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -200,7 +199,7 @@ func NewCompatServiceJSONClient(baseURL string, client HTTPClient, opts ...twirp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -335,7 +334,7 @@ type compatServiceServer struct {
 func NewCompatServiceServer(svc CompatService, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -536,7 +535,7 @@ func (s *compatServiceServer) serveMethodProtobuf(ctx context.Context, resp http
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -716,7 +715,7 @@ func (s *compatServiceServer) serveNoopMethodProtobuf(ctx context.Context, resp
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -910,7 +909,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -924,9 +923,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -1032,7 +1034,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -1232,7 +1234,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/example/service.pb.go b/example/service.pb.go
index 17641a36..f0493d65 100644
--- a/example/service.pb.go
+++ b/example/service.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: service.proto
 
diff --git a/example/service.twirp.go b/example/service.twirp.go
index e409baaf..691c024a 100644
--- a/example/service.twirp.go
+++ b/example/service.twirp.go
@@ -6,7 +6,7 @@ package example
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewHaberdasherProtobufClient(baseURL string, client HTTPClient, opts ...twi
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewHaberdasherJSONClient(baseURL string, client HTTPClient, opts ...twirp.C
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type haberdasherServer struct {
 func NewHaberdasherServer(svc Haberdasher, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *haberdasherServer) serveMakeHatProtobuf(ctx context.Context, resp http.
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/descriptors/descriptors.go b/internal/descriptors/descriptors.go
index 74e86707..67af4e85 100644
--- a/internal/descriptors/descriptors.go
+++ b/internal/descriptors/descriptors.go
@@ -18,7 +18,7 @@ package descriptors
 import (
 	"bytes"
 	"compress/gzip"
-	"io/ioutil"
+	"io"
 
 	"google.golang.org/protobuf/proto"
 	protobuf "google.golang.org/protobuf/types/descriptorpb"
@@ -36,7 +36,7 @@ func UnpackFile(gz []byte) (*protobuf.FileDescriptorProto, error) {
 	}
 	defer r.Close()
 
-	b, err := ioutil.ReadAll(r)
+	b, err := io.ReadAll(r)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to uncompress descriptor")
 	}
diff --git a/internal/gen/main.go b/internal/gen/main.go
index 7aa5ba76..c5fb7288 100644
--- a/internal/gen/main.go
+++ b/internal/gen/main.go
@@ -15,7 +15,6 @@ package gen
 
 import (
 	"io"
-	"io/ioutil"
 	"os"
 
 	"google.golang.org/protobuf/proto"
@@ -50,7 +49,7 @@ Outer:
 }
 
 func readGenRequest(r io.Reader) *plugin.CodeGeneratorRequest {
-	data, err := ioutil.ReadAll(r)
+	data, err := io.ReadAll(r)
 	if err != nil {
 		Error(err, "reading input")
 	}
diff --git a/internal/gen/typemap/typemap_test.go b/internal/gen/typemap/typemap_test.go
index 6f480f0d..53de5052 100644
--- a/internal/gen/typemap/typemap_test.go
+++ b/internal/gen/typemap/typemap_test.go
@@ -14,7 +14,7 @@
 package typemap
 
 import (
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -25,7 +25,7 @@ import (
 )
 
 func loadTestPb(t *testing.T) []*descriptor.FileDescriptorProto {
-	f, err := ioutil.ReadFile(filepath.Join("testdata", "fileset.pb"))
+	f, err := os.ReadFile(filepath.Join("testdata", "fileset.pb"))
 	require.NoError(t, err, "unable to read testdata protobuf file")
 
 	set := new(descriptor.FileDescriptorSet)
diff --git a/internal/twirptest/empty_service/empty_service.pb.go b/internal/twirptest/empty_service/empty_service.pb.go
index 0f195510..f1381ec7 100644
--- a/internal/twirptest/empty_service/empty_service.pb.go
+++ b/internal/twirptest/empty_service/empty_service.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: empty_service.proto
 
diff --git a/internal/twirptest/empty_service/empty_service.twirp.go b/internal/twirptest/empty_service/empty_service.twirp.go
index 071b0143..37a667de 100644
--- a/internal/twirptest/empty_service/empty_service.twirp.go
+++ b/internal/twirptest/empty_service/empty_service.twirp.go
@@ -6,7 +6,7 @@ package empty_service
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -58,7 +57,7 @@ func NewEmptyProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Cli
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -99,7 +98,7 @@ func NewEmptyJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientO
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -136,7 +135,7 @@ type emptyServer struct {
 func NewEmptyServer(svc Empty, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -345,7 +344,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -359,9 +358,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -467,7 +469,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -667,7 +669,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/google_protobuf_imports/service.pb.go b/internal/twirptest/google_protobuf_imports/service.pb.go
index c6a4a60c..36569391 100644
--- a/internal/twirptest/google_protobuf_imports/service.pb.go
+++ b/internal/twirptest/google_protobuf_imports/service.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: service.proto
 
diff --git a/internal/twirptest/google_protobuf_imports/service.twirp.go b/internal/twirptest/google_protobuf_imports/service.twirp.go
index fb5365e5..b5025c8f 100644
--- a/internal/twirptest/google_protobuf_imports/service.twirp.go
+++ b/internal/twirptest/google_protobuf_imports/service.twirp.go
@@ -6,7 +6,7 @@ package google_protobuf_imports
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -21,7 +21,6 @@ import google_protobuf1 "google.golang.org/protobuf/types/known/wrapperspb"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -62,7 +61,7 @@ func NewSvcProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clien
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -154,7 +153,7 @@ func NewSvcJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOpt
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -242,7 +241,7 @@ type svcServer struct {
 func NewSvcServer(svc Svc, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -440,7 +439,7 @@ func (s *svcServer) serveSendProtobuf(ctx context.Context, resp http.ResponseWri
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -634,7 +633,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -648,9 +647,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -756,7 +758,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -956,7 +958,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/importable/importable.pb.go b/internal/twirptest/importable/importable.pb.go
index 61f2469b..374d40a8 100644
--- a/internal/twirptest/importable/importable.pb.go
+++ b/internal/twirptest/importable/importable.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: importable.proto
 
diff --git a/internal/twirptest/importable/importable.twirp.go b/internal/twirptest/importable/importable.twirp.go
index d0581012..bd7e79dc 100644
--- a/internal/twirptest/importable/importable.twirp.go
+++ b/internal/twirptest/importable/importable.twirp.go
@@ -8,7 +8,7 @@ package importable
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -20,7 +20,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewSvcProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clien
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewSvcJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOpt
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type svcServer struct {
 func NewSvcServer(svc Svc, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *svcServer) serveSendProtobuf(ctx context.Context, resp http.ResponseWri
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -633,7 +632,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/importer/importer.pb.go b/internal/twirptest/importer/importer.pb.go
index 3bf15e33..e28a0fae 100644
--- a/internal/twirptest/importer/importer.pb.go
+++ b/internal/twirptest/importer/importer.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: importer.proto
 
diff --git a/internal/twirptest/importer/importer.twirp.go b/internal/twirptest/importer/importer.twirp.go
index 0e53f092..4a773b12 100644
--- a/internal/twirptest/importer/importer.twirp.go
+++ b/internal/twirptest/importer/importer.twirp.go
@@ -8,7 +8,7 @@ package importer
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -22,7 +22,6 @@ import twirp_internal_twirptest_importable "github.com/twitchtv/twirp/internal/t
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -63,7 +62,7 @@ func NewSvc2ProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -155,7 +154,7 @@ func NewSvc2JSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -243,7 +242,7 @@ type svc2Server struct {
 func NewSvc2Server(svc Svc2, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -441,7 +440,7 @@ func (s *svc2Server) serveSendProtobuf(ctx context.Context, resp http.ResponseWr
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -635,7 +634,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -649,9 +648,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -757,7 +759,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -957,7 +959,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/importer_local/importer_local.pb.go b/internal/twirptest/importer_local/importer_local.pb.go
index b53ec1d3..e011ca8e 100644
--- a/internal/twirptest/importer_local/importer_local.pb.go
+++ b/internal/twirptest/importer_local/importer_local.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: importer_local.proto
 
diff --git a/internal/twirptest/importer_local/importer_local.twirp.go b/internal/twirptest/importer_local/importer_local.twirp.go
index 56bc399b..a76bf214 100644
--- a/internal/twirptest/importer_local/importer_local.twirp.go
+++ b/internal/twirptest/importer_local/importer_local.twirp.go
@@ -6,7 +6,7 @@ package importer_local
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -59,7 +58,7 @@ func NewSvcProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clien
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -151,7 +150,7 @@ func NewSvcJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOpt
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -239,7 +238,7 @@ type svcServer struct {
 func NewSvcServer(svc Svc, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -437,7 +436,7 @@ func (s *svcServer) serveSendProtobuf(ctx context.Context, resp http.ResponseWri
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -631,7 +630,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -645,9 +644,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -753,7 +755,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -953,7 +955,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/importer_local/importer_local_msgdef.pb.go b/internal/twirptest/importer_local/importer_local_msgdef.pb.go
index 32ab8321..d1520c03 100644
--- a/internal/twirptest/importer_local/importer_local_msgdef.pb.go
+++ b/internal/twirptest/importer_local/importer_local_msgdef.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: importer_local_msgdef.proto
 
diff --git a/internal/twirptest/importmapping/x/x.pb.go b/internal/twirptest/importmapping/x/x.pb.go
index a455cff3..23721f96 100644
--- a/internal/twirptest/importmapping/x/x.pb.go
+++ b/internal/twirptest/importmapping/x/x.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: x/x.proto
 
diff --git a/internal/twirptest/importmapping/x/x.twirp.go b/internal/twirptest/importmapping/x/x.twirp.go
index 16804971..50081d25 100644
--- a/internal/twirptest/importmapping/x/x.twirp.go
+++ b/internal/twirptest/importmapping/x/x.twirp.go
@@ -6,7 +6,7 @@ package x
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -20,7 +20,6 @@ import twirp_internal_twirptest_importmapping_y "github.com/twitchtv/twirp/inter
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewSvc1ProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewSvc1JSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type svc1Server struct {
 func NewSvc1Server(svc Svc1, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *svc1Server) serveSendProtobuf(ctx context.Context, resp http.ResponseWr
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -633,7 +632,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/importmapping/y/y.pb.go b/internal/twirptest/importmapping/y/y.pb.go
index 8cea861d..c8152e2d 100644
--- a/internal/twirptest/importmapping/y/y.pb.go
+++ b/internal/twirptest/importmapping/y/y.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: y/y.proto
 
diff --git a/internal/twirptest/json_serialization/json_serialization.pb.go b/internal/twirptest/json_serialization/json_serialization.pb.go
index 2f3ba2eb..5a163422 100644
--- a/internal/twirptest/json_serialization/json_serialization.pb.go
+++ b/internal/twirptest/json_serialization/json_serialization.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: json_serialization.proto
 
diff --git a/internal/twirptest/json_serialization/json_serialization.twirp.go b/internal/twirptest/json_serialization/json_serialization.twirp.go
index 81286392..70270910 100644
--- a/internal/twirptest/json_serialization/json_serialization.twirp.go
+++ b/internal/twirptest/json_serialization/json_serialization.twirp.go
@@ -6,7 +6,7 @@ package json_serialization
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -59,7 +58,7 @@ func NewJSONSerializationProtobufClient(baseURL string, client HTTPClient, opts
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -151,7 +150,7 @@ func NewJSONSerializationJSONClient(baseURL string, client HTTPClient, opts ...t
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -239,7 +238,7 @@ type jSONSerializationServer struct {
 func NewJSONSerializationServer(svc JSONSerialization, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -437,7 +436,7 @@ func (s *jSONSerializationServer) serveEchoJSONProtobuf(ctx context.Context, res
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -631,7 +630,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -645,9 +644,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -753,7 +755,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -953,7 +955,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/multiple/multiple1.pb.go b/internal/twirptest/multiple/multiple1.pb.go
index 0d5a5f81..4667dff5 100644
--- a/internal/twirptest/multiple/multiple1.pb.go
+++ b/internal/twirptest/multiple/multiple1.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: multiple1.proto
 
diff --git a/internal/twirptest/multiple/multiple1.twirp.go b/internal/twirptest/multiple/multiple1.twirp.go
index 3e381fbc..ac9e95bb 100644
--- a/internal/twirptest/multiple/multiple1.twirp.go
+++ b/internal/twirptest/multiple/multiple1.twirp.go
@@ -8,7 +8,7 @@ package multiple
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -20,7 +20,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewSvc1ProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewSvc1JSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type svc1Server struct {
 func NewSvc1Server(svc Svc1, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *svc1Server) serveSendProtobuf(ctx context.Context, resp http.ResponseWr
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -633,7 +632,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/multiple/multiple2.pb.go b/internal/twirptest/multiple/multiple2.pb.go
index 4ddd6ea0..8e95c390 100644
--- a/internal/twirptest/multiple/multiple2.pb.go
+++ b/internal/twirptest/multiple/multiple2.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: multiple2.proto
 
diff --git a/internal/twirptest/multiple/multiple2.twirp.go b/internal/twirptest/multiple/multiple2.twirp.go
index 23afb26e..6d47ce74 100644
--- a/internal/twirptest/multiple/multiple2.twirp.go
+++ b/internal/twirptest/multiple/multiple2.twirp.go
@@ -8,7 +8,7 @@ package multiple
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -57,7 +57,7 @@ func NewSvc2ProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -196,7 +196,7 @@ func NewSvc2JSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -331,7 +331,7 @@ type svc2Server struct {
 func NewSvc2Server(svc Svc2, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -532,7 +532,7 @@ func (s *svc2Server) serveSendProtobuf(ctx context.Context, resp http.ResponseWr
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -712,7 +712,7 @@ func (s *svc2Server) serveSamePackageProtoImportProtobuf(ctx context.Context, re
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
diff --git a/internal/twirptest/no_package_name/no_package_name.pb.go b/internal/twirptest/no_package_name/no_package_name.pb.go
index 15db2012..46762680 100644
--- a/internal/twirptest/no_package_name/no_package_name.pb.go
+++ b/internal/twirptest/no_package_name/no_package_name.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: no_package_name.proto
 
diff --git a/internal/twirptest/no_package_name/no_package_name.twirp.go b/internal/twirptest/no_package_name/no_package_name.twirp.go
index ac8c2cb9..1231b756 100644
--- a/internal/twirptest/no_package_name/no_package_name.twirp.go
+++ b/internal/twirptest/no_package_name/no_package_name.twirp.go
@@ -6,7 +6,7 @@ package no_package_name
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -59,7 +58,7 @@ func NewSvcProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clien
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -151,7 +150,7 @@ func NewSvcJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOpt
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -239,7 +238,7 @@ type svcServer struct {
 func NewSvcServer(svc Svc, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -437,7 +436,7 @@ func (s *svcServer) serveSendProtobuf(ctx context.Context, resp http.ResponseWri
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -631,7 +630,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -645,9 +644,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -753,7 +755,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -953,7 +955,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/no_package_name_importer/no_package_name_importer.pb.go b/internal/twirptest/no_package_name_importer/no_package_name_importer.pb.go
index a2d5b606..17be3ce1 100644
--- a/internal/twirptest/no_package_name_importer/no_package_name_importer.pb.go
+++ b/internal/twirptest/no_package_name_importer/no_package_name_importer.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: no_package_name_importer/no_package_name_importer.proto
 
diff --git a/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go b/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go
index fa6900f9..b517cd46 100644
--- a/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go
+++ b/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go
@@ -6,7 +6,7 @@ package no_package_name_importer
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -20,7 +20,6 @@ import no_package_name "github.com/twitchtv/twirp/internal/twirptest/no_package_
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewSvc2ProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewSvc2JSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type svc2Server struct {
 func NewSvc2Server(svc Svc2, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *svc2Server) serveMethodProtobuf(ctx context.Context, resp http.Response
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -633,7 +632,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/service.pb.go b/internal/twirptest/service.pb.go
index 2f4e7715..159193eb 100644
--- a/internal/twirptest/service.pb.go
+++ b/internal/twirptest/service.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: service.proto
 
diff --git a/internal/twirptest/service.twirp.go b/internal/twirptest/service.twirp.go
index 3e763b88..c3bb6890 100644
--- a/internal/twirptest/service.twirp.go
+++ b/internal/twirptest/service.twirp.go
@@ -6,7 +6,7 @@ package twirptest
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -61,7 +60,7 @@ func NewHaberdasherProtobufClient(baseURL string, client HTTPClient, opts ...twi
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -153,7 +152,7 @@ func NewHaberdasherJSONClient(baseURL string, client HTTPClient, opts ...twirp.C
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -241,7 +240,7 @@ type haberdasherServer struct {
 func NewHaberdasherServer(svc Haberdasher, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -439,7 +438,7 @@ func (s *haberdasherServer) serveMakeHatProtobuf(ctx context.Context, resp http.
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -633,7 +632,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -647,9 +646,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -755,7 +757,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -955,7 +957,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/service_method_same_name/service_method_same_name.pb.go b/internal/twirptest/service_method_same_name/service_method_same_name.pb.go
index 1ccb9096..d3071a7f 100644
--- a/internal/twirptest/service_method_same_name/service_method_same_name.pb.go
+++ b/internal/twirptest/service_method_same_name/service_method_same_name.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: service_method_same_name.proto
 
diff --git a/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go b/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go
index 7d94cb60..5acd7a21 100644
--- a/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go
+++ b/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go
@@ -6,7 +6,7 @@ package service_method_same_name
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -18,7 +18,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -59,7 +58,7 @@ func NewEchoProtobufClient(baseURL string, client HTTPClient, opts ...twirp.Clie
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -151,7 +150,7 @@ func NewEchoJSONClient(baseURL string, client HTTPClient, opts ...twirp.ClientOp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -239,7 +238,7 @@ type echoServer struct {
 func NewEchoServer(svc Echo, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -437,7 +436,7 @@ func (s *echoServer) serveEchoProtobuf(ctx context.Context, resp http.ResponseWr
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -631,7 +630,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -645,9 +644,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -753,7 +755,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -953,7 +955,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/internal/twirptest/service_test.go b/internal/twirptest/service_test.go
index 8dbb8122..9980914b 100644
--- a/internal/twirptest/service_test.go
+++ b/internal/twirptest/service_test.go
@@ -20,10 +20,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"reflect"
 	"regexp"
 	"strings"
@@ -83,7 +83,7 @@ func TestServerJSONWithMalformedRequest(t *testing.T) {
 		t.Fatalf("Expected 400 BadRequest when sending malformed request, got %d", resp.StatusCode)
 	}
 	// Make sure the response is meaningful
-	respBytes, err := ioutil.ReadAll(resp.Body)
+	respBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatalf("Could not even read bytes from response: %q", err.Error())
 	}
@@ -114,7 +114,7 @@ func TestServerJSONWithUnknownFields(t *testing.T) {
 	}()
 
 	// Make sure that the returned hat is valid and has empty (zero-value) size
-	respBytes, err := ioutil.ReadAll(resp.Body) // read manually first in case jsonpb.Unmarshal so it can be printed for debugging
+	respBytes, err := io.ReadAll(resp.Body) // read manually first in case jsonpb.Unmarshal so it can be printed for debugging
 	if err != nil {
 		t.Fatalf("Could not even read bytes from response: %q", err.Error())
 	}
@@ -149,7 +149,7 @@ func TestServerProtobufMalformedRequest(t *testing.T) {
 		t.Fatalf("Expected 400 BadRequest when sending malformed request, got %d", resp.StatusCode)
 	}
 	// Make sure the response is meaningful
-	respBytes, err := ioutil.ReadAll(resp.Body)
+	respBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatalf("Could not even read bytes from response: %q", err.Error())
 	}
@@ -436,7 +436,7 @@ func TestHooks(t *testing.T) {
 			base: http.DefaultTransport,
 			rewrite: func(r *http.Request) *http.Request {
 				r.ContentLength = 1
-				r.Body = ioutil.NopCloser(io.LimitReader(r.Body, 1))
+				r.Body = io.NopCloser(io.LimitReader(r.Body, 1))
 				return r
 			},
 		}
@@ -987,7 +987,7 @@ func testMuxingTwirpServer(t *testing.T, prefix string, handler TwirpServer) {
 		t.Errorf("health check endpoint err=%q", err)
 	} else {
 		if resp.StatusCode != 200 {
-			body, err := ioutil.ReadAll(resp.Body)
+			body, err := io.ReadAll(resp.Body)
 			t.Errorf("got a non-200 response from /health: %d", resp.StatusCode)
 			t.Logf("response body: %s", body)
 			t.Logf("response read err: %s", err)
@@ -1451,7 +1451,7 @@ func TestReflection(t *testing.T) {
 	})
 	t.Run("ProtoGenTwirpVersion", func(t *testing.T) {
 		// Should match whatever is in the file at protoc-gen-twirp/version.go
-		file, err := ioutil.ReadFile("../gen/version.go")
+		file, err := os.ReadFile("../gen/version.go")
 		if err != nil {
 			t.Fatalf("unable to load version file: %v", err)
 		}
@@ -1657,7 +1657,7 @@ func TestRequestBodyError(t *testing.T) {
 			}
 
 			// validate error message
-			respBytes, err := ioutil.ReadAll(w.Body)
+			respBytes, err := io.ReadAll(w.Body)
 			if err != nil {
 				t.Fatalf("Could not even read bytes from response: %q", err.Error())
 			}
diff --git a/internal/twirptest/snake_case_names/snake_case_names.pb.go b/internal/twirptest/snake_case_names/snake_case_names.pb.go
index e8ffa7f8..07b9009a 100644
--- a/internal/twirptest/snake_case_names/snake_case_names.pb.go
+++ b/internal/twirptest/snake_case_names/snake_case_names.pb.go
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.26.0-devel
+// 	protoc-gen-go v1.28.0
 // 	protoc        v3.19.4
 // source: snake_case_names.proto
 
diff --git a/internal/twirptest/snake_case_names/snake_case_names.twirp.go b/internal/twirptest/snake_case_names/snake_case_names.twirp.go
index d569fa48..2a8de785 100644
--- a/internal/twirptest/snake_case_names/snake_case_names.twirp.go
+++ b/internal/twirptest/snake_case_names/snake_case_names.twirp.go
@@ -9,7 +9,7 @@ package snake_case_names
 import context "context"
 import fmt "fmt"
 import http "net/http"
-import ioutil "io/ioutil"
+import io "io"
 import json "encoding/json"
 import strconv "strconv"
 import strings "strings"
@@ -21,7 +21,6 @@ import ctxsetters "github.com/twitchtv/twirp/ctxsetters"
 
 import bytes "bytes"
 import errors "errors"
-import io "io"
 import path "path"
 import url "net/url"
 
@@ -63,7 +62,7 @@ func NewHaberdasherV1ProtobufClient(baseURL string, client HTTPClient, opts ...t
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -164,7 +163,7 @@ func NewHaberdasherV1JSONClient(baseURL string, client HTTPClient, opts ...twirp
 		o(&clientOpts)
 	}
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	literalURLs := false
 	_ = clientOpts.ReadOpt("literalURLs", &literalURLs)
 	var pathPrefix string
@@ -261,7 +260,7 @@ type haberdasherV1Server struct {
 func NewHaberdasherV1Server(svc HaberdasherV1, opts ...interface{}) TwirpServer {
 	serverOpts := newServerOpts(opts)
 
-	// Using ReadOpt allows backwards and forwads compatibility with new options in the future
+	// Using ReadOpt allows backwards and forwards compatibility with new options in the future
 	jsonSkipDefaults := false
 	_ = serverOpts.ReadOpt("jsonSkipDefaults", &jsonSkipDefaults)
 	jsonCamelCase := false
@@ -459,7 +458,7 @@ func (s *haberdasherV1Server) serveMakeHatV1Protobuf(ctx context.Context, resp h
 		return
 	}
 
-	buf, err := ioutil.ReadAll(req.Body)
+	buf, err := io.ReadAll(req.Body)
 	if err != nil {
 		s.handleRequestBodyError(ctx, resp, "failed to read request body", err)
 		return
@@ -653,7 +652,7 @@ func writeError(ctx context.Context, resp http.ResponseWriter, err error, hooks
 }
 
 // sanitizeBaseURL parses the the baseURL, and adds the "http" scheme if needed.
-// If the URL is unparsable, the baseURL is returned unchaged.
+// If the URL is unparsable, the baseURL is returned unchanged.
 func sanitizeBaseURL(baseURL string) string {
 	u, err := url.Parse(baseURL)
 	if err != nil {
@@ -667,9 +666,12 @@ func sanitizeBaseURL(baseURL string) string {
 
 // baseServicePath composes the path prefix for the service (without <Method>).
 // e.g.: baseServicePath("/twirp", "my.pkg", "MyService")
-//       returns => "/twirp/my.pkg.MyService/"
+//
+//	returns => "/twirp/my.pkg.MyService/"
+//
 // e.g.: baseServicePath("", "", "MyService")
-//       returns => "/MyService/"
+//
+//	returns => "/MyService/"
 func baseServicePath(prefix, pkg, service string) string {
 	fullServiceName := service
 	if pkg != "" {
@@ -775,7 +777,7 @@ func errorFromResponse(resp *http.Response) twirp.Error {
 		return twirpErrorFromIntermediary(statusCode, msg, location)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return wrapInternal(err, "failed to read server error response body")
 	}
@@ -975,7 +977,7 @@ func doProtobufRequest(ctx context.Context, client HTTPClient, hooks *twirp.Clie
 		return ctx, errorFromResponse(resp)
 	}
 
-	respBodyBytes, err := ioutil.ReadAll(resp.Body)
+	respBodyBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return ctx, wrapInternal(err, "failed to read response body")
 	}
diff --git a/license_test.go b/license_test.go
index 5cb3d751..5309f63b 100644
--- a/license_test.go
+++ b/license_test.go
@@ -16,7 +16,6 @@ package twirp
 import (
 	"bytes"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -64,7 +63,7 @@ func TestSourceCodeLicenseHeaders(t *testing.T) {
 		if err != nil {
 			return err
 		}
-		fileBytes, err := ioutil.ReadAll(file)
+		fileBytes, err := io.ReadAll(file)
 		if err != nil {
 			return err
 		}
diff --git a/protoc-gen-twirp/generator.go b/protoc-gen-twirp/generator.go
index 73916324..601f80fd 100644
--- a/protoc-gen-twirp/generator.go
+++ b/protoc-gen-twirp/generator.go
@@ -100,7 +100,6 @@ func (t *twirp) Generate(in *plugin.CodeGeneratorRequest) *plugin.CodeGeneratorR
 	t.registerPackageName("context")
 	t.registerPackageName("http")
 	t.registerPackageName("io")
-	t.registerPackageName("ioutil")
 	t.registerPackageName("json")
 	t.registerPackageName("protojson")
 	t.registerPackageName("proto")
@@ -286,7 +285,7 @@ func (t *twirp) generateImports(file *descriptor.FileDescriptorProto) {
 	t.P(`import `, t.pkgs["context"], ` "context"`)
 	t.P(`import `, t.pkgs["fmt"], ` "fmt"`)
 	t.P(`import `, t.pkgs["http"], ` "net/http"`)
-	t.P(`import `, t.pkgs["ioutil"], ` "io/ioutil"`)
+	t.P(`import `, t.pkgs["io"], ` "io"`)
 	t.P(`import `, t.pkgs["json"], ` "encoding/json"`)
 	t.P(`import `, t.pkgs["strconv"], ` "strconv"`)
 	t.P(`import `, t.pkgs["strings"], ` "strings"`)
@@ -349,7 +348,6 @@ func (t *twirp) generateImports(file *descriptor.FileDescriptorProto) {
 func (t *twirp) generateUtilImports() {
 	t.P(`import `, t.pkgs["bytes"], ` "bytes"`)
 	t.P(`import `, t.pkgs["errors"], ` "errors"`)
-	t.P(`import `, t.pkgs["io"], ` "io"`)
 	t.P(`import `, t.pkgs["path"], ` "path"`)
 	t.P(`import `, t.pkgs["url"], ` "net/url"`)
 }
@@ -599,7 +597,7 @@ func (t *twirp) generateUtils() {
 	t.P(`    return twirpErrorFromIntermediary(statusCode, msg, location)`)
 	t.P(`  }`)
 	t.P(``)
-	t.P(`  respBodyBytes, err := `, t.pkgs["ioutil"], `.ReadAll(resp.Body)`)
+	t.P(`  respBodyBytes, err := `, t.pkgs["io"], `.ReadAll(resp.Body)`)
 	t.P(`  if err != nil {`)
 	t.P(`    return wrapInternal(err, "failed to read server error response body")`)
 	t.P(`  }`)
@@ -804,7 +802,7 @@ func (t *twirp) generateUtils() {
 	t.P(`    return ctx, errorFromResponse(resp)`)
 	t.P(`  }`)
 	t.P()
-	t.P(`  respBodyBytes, err := `, t.pkgs["ioutil"], `.ReadAll(resp.Body)`)
+	t.P(`  respBodyBytes, err := `, t.pkgs["io"], `.ReadAll(resp.Body)`)
 	t.P(`  if err != nil {`)
 	t.P(`    return ctx, wrapInternal(err, "failed to read response body")`)
 	t.P(`  }`)
@@ -1384,7 +1382,7 @@ func (t *twirp) generateServerProtobufMethod(service *descriptor.ServiceDescript
 	t.P(`    return`)
 	t.P(`  }`)
 	t.P()
-	t.P(`  buf, err := `, t.pkgs["ioutil"], `.ReadAll(req.Body)`)
+	t.P(`  buf, err := `, t.pkgs["io"], `.ReadAll(req.Body)`)
 	t.P(`  if err != nil {`)
 	t.P(`    s.handleRequestBodyError(ctx, resp, "failed to read request body", err)`)
 	t.P(`    return`)