diff --git a/Gemfile.lock b/Gemfile.lock
index f136078..d43db8e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -13,7 +13,7 @@ GEM
     google-protobuf (3.11.2)
     minitest (5.11.3)
     multipart-post (2.1.1)
-    rack (2.0.7)
+    rack (2.0.8)
     rake (12.3.1)
 
 PLATFORMS
@@ -22,7 +22,7 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 1)
   minitest (>= 5)
-  rack
+  rack (>= 2.0.8)
   rake
   twirp!
 
diff --git a/twirp.gemspec b/twirp.gemspec
index b2304a6..cd96aca 100644
--- a/twirp.gemspec
+++ b/twirp.gemspec
@@ -25,5 +25,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'bundler', '~> 1'
   spec.add_development_dependency 'minitest', '>= 5'
   spec.add_development_dependency 'rake'
-  spec.add_development_dependency 'rack'
+  spec.add_development_dependency 'rack', '>= 2.0.8'
 end