diff --git a/cert.go b/cert.go
index 0d4a1bef..93684b97 100644
--- a/cert.go
+++ b/cert.go
@@ -90,7 +90,7 @@ func (n *Name) AddTextEntry(field, value string) error {
 	defer C.free(unsafe.Pointer(cvalue))
 	ret := C.X509_NAME_add_entry_by_txt(
 		n.name, cfield, C.MBSTRING_ASC, cvalue, -1, -1, 0)
-	if ret == 0 {
+	if ret <= 0 {
 		return errors.New("failed to add x509 name text entry")
 	}
 	return nil
@@ -162,7 +162,7 @@ func (c *Certificate) GetIssuerName() (*Name, error) {
 }
 
 func (c *Certificate) SetSubjectName(name *Name) error {
-	if C.X509_set_subject_name(c.x, name.name) == 0 {
+	if C.X509_set_subject_name(c.x, name.name) <= 0 {
 		return errors.New("failed to set subject name")
 	}
 	return nil
@@ -186,7 +186,7 @@ func (c *Certificate) SetIssuer(issuer *Certificate) error {
 // SetIssuerName populates the issuer name of a certificate.
 // Use SetIssuer instead, if possible.
 func (c *Certificate) SetIssuerName(name *Name) error {
-	if C.X509_set_issuer_name(c.x, name.name) == 0 {
+	if C.X509_set_issuer_name(c.x, name.name) <= 0 {
 		return errors.New("failed to set subject name")
 	}
 	return nil
@@ -194,7 +194,7 @@ func (c *Certificate) SetIssuerName(name *Name) error {
 
 // SetSerial sets the serial of a certificate.
 func (c *Certificate) SetSerial(serial int) error {
-	if C.ASN1_INTEGER_set(C.X509_get_serialNumber(c.x), C.long(serial)) == 0 {
+	if C.ASN1_INTEGER_set(C.X509_get_serialNumber(c.x), C.long(serial)) <= 0 {
 		return errors.New("failed to set serial")
 	}
 	return nil
@@ -223,7 +223,7 @@ func (c *Certificate) SetExpireDate(when time.Duration) error {
 // SetPubKey assigns a new public key to a certificate.
 func (c *Certificate) SetPubKey(pubKey PublicKey) error {
 	c.pubKey = pubKey
-	if C.X509_set_pubkey(c.x, pubKey.evpPKey()) == 0 {
+	if C.X509_set_pubkey(c.x, pubKey.evpPKey()) <= 0 {
 		return errors.New("failed to set public key")
 	}
 	return nil
@@ -271,7 +271,7 @@ func (c *Certificate) insecureSign(privKey PrivateKey, digest EVP_MD) error {
 	case EVP_SHA512:
 		md = C.EVP_sha512()
 	}
-	if C.X509_sign(c.x, privKey.evpPKey(), md) == 0 {
+	if C.X509_sign(c.x, privKey.evpPKey(), md) <= 0 {
 		return errors.New("failed to sign certificate")
 	}
 	return nil
@@ -291,7 +291,7 @@ func (c *Certificate) AddExtension(nid NID, value string) error {
 		return errors.New("failed to create x509v3 extension")
 	}
 	defer C.X509_EXTENSION_free(ex)
-	if C.X509_add_ext(c.x, ex, -1) == 0 {
+	if C.X509_add_ext(c.x, ex, -1) <= 0 {
 		return errors.New("failed to add x509v3 extension")
 	}
 	return nil
@@ -310,7 +310,7 @@ func (c *Certificate) AddExtensions(extensions map[NID]string) error {
 
 // LoadCertificateFromPEM loads an X509 certificate from a PEM-encoded block.
 func LoadCertificateFromPEM(pem_block []byte) (*Certificate, error) {
-	if len(pem_block) == 0 {
+	if len(pem_block) <= 0 {
 		return nil, errors.New("empty pem block")
 	}
 	runtime.LockOSThread()
@@ -336,7 +336,7 @@ func (c *Certificate) MarshalPEM() (pem_block []byte, err error) {
 		return nil, errors.New("failed to allocate memory BIO")
 	}
 	defer C.BIO_free(bio)
-	if int(C.PEM_write_bio_X509(bio, c.x)) != 1 {
+	if int(C.PEM_write_bio_X509(bio, c.x)) <= 0 {
 		return nil, errors.New("failed dumping certificate")
 	}
 	return ioutil.ReadAll(asAnyBio(bio))
diff --git a/ciphers.go b/ciphers.go
index 17d48e84..47e1325e 100644
--- a/ciphers.go
+++ b/ciphers.go
@@ -153,7 +153,7 @@ func (ctx *cipherCtx) applyKeyAndIV(key, iv []byte) error {
 		iptr = (*C.uchar)(&iv[0])
 	}
 	if kptr != nil || iptr != nil {
-		if 1 != C.EVP_EncryptInit_ex(ctx.ctx, nil, nil, kptr, iptr) {
+		if 0 >= C.EVP_EncryptInit_ex(ctx.ctx, nil, nil, kptr, iptr) {
 			return errors.New("failed to apply key/IV")
 		}
 	}
@@ -178,9 +178,8 @@ func (ctx *cipherCtx) IVSize() int {
 
 func (ctx *cipherCtx) setCtrl(code, arg int) error {
 	res := C.EVP_CIPHER_CTX_ctrl(ctx.ctx, C.int(code), C.int(arg), nil)
-	if res != 1 {
-		return fmt.Errorf("failed to set code %d to %d [result %d]",
-			code, arg, res)
+	if res <= 0 {
+		return fmt.Errorf("failed to set code %d to %d", code, arg)
 	}
 	return nil
 }
@@ -188,9 +187,9 @@ func (ctx *cipherCtx) setCtrl(code, arg int) error {
 func (ctx *cipherCtx) setCtrlBytes(code, arg int, value []byte) error {
 	res := C.EVP_CIPHER_CTX_ctrl(ctx.ctx, C.int(code), C.int(arg),
 		unsafe.Pointer(&value[0]))
-	if res != 1 {
-		return fmt.Errorf("failed to set code %d with arg %d to %x [result %d]",
-			code, arg, value, res)
+	if res <= 0 {
+		return fmt.Errorf("failed to set code %d with arg %d to %x",
+			code, arg, value)
 	}
 	return nil
 }
@@ -199,9 +198,8 @@ func (ctx *cipherCtx) getCtrlInt(code, arg int) (int, error) {
 	var returnVal C.int
 	res := C.EVP_CIPHER_CTX_ctrl(ctx.ctx, C.int(code), C.int(arg),
 		unsafe.Pointer(&returnVal))
-	if res != 1 {
-		return 0, fmt.Errorf("failed to get code %d with arg %d [result %d]",
-			code, arg, res)
+	if res <= 0 {
+		return 0, fmt.Errorf("failed to get code %d with arg %d", code, arg)
 	}
 	return int(returnVal), nil
 }
@@ -210,9 +208,8 @@ func (ctx *cipherCtx) getCtrlBytes(code, arg, expectsize int) ([]byte, error) {
 	returnVal := make([]byte, expectsize)
 	res := C.EVP_CIPHER_CTX_ctrl(ctx.ctx, C.int(code), C.int(arg),
 		unsafe.Pointer(&returnVal[0]))
-	if res != 1 {
-		return nil, fmt.Errorf("failed to get code %d with arg %d [result %d]",
-			code, arg, res)
+	if res <= 0 {
+		return nil, fmt.Errorf("failed to get code %d with arg %d", code, arg)
 	}
 	return returnVal, nil
 }
@@ -263,7 +260,7 @@ func newEncryptionCipherCtx(c *Cipher, e *Engine, key, iv []byte) (
 	if e != nil {
 		eptr = e.e
 	}
-	if 1 != C.EVP_EncryptInit_ex(ctx.ctx, c.ptr, eptr, nil, nil) {
+	if 0 >= C.EVP_EncryptInit_ex(ctx.ctx, c.ptr, eptr, nil, nil) {
 		return nil, errors.New("failed to initialize cipher context")
 	}
 	err = ctx.applyKeyAndIV(key, iv)
@@ -286,7 +283,7 @@ func newDecryptionCipherCtx(c *Cipher, e *Engine, key, iv []byte) (
 	if e != nil {
 		eptr = e.e
 	}
-	if 1 != C.EVP_DecryptInit_ex(ctx.ctx, c.ptr, eptr, nil, nil) {
+	if 0 >= C.EVP_DecryptInit_ex(ctx.ctx, c.ptr, eptr, nil, nil) {
 		return nil, errors.New("failed to initialize cipher context")
 	}
 	err = ctx.applyKeyAndIV(key, iv)
@@ -311,8 +308,8 @@ func (ctx *encryptionCipherCtx) EncryptUpdate(input []byte) ([]byte, error) {
 	outlen := C.int(len(outbuf))
 	res := C.EVP_EncryptUpdate(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen,
 		(*C.uchar)(&input[0]), C.int(len(input)))
-	if res != 1 {
-		return nil, fmt.Errorf("failed to encrypt [result %d]", res)
+	if res <= 0 {
+		return nil, fmt.Errorf("failed to encrypt")
 	}
 	return outbuf[:outlen], nil
 }
@@ -322,8 +319,8 @@ func (ctx *decryptionCipherCtx) DecryptUpdate(input []byte) ([]byte, error) {
 	outlen := C.int(len(outbuf))
 	res := C.EVP_DecryptUpdate(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen,
 		(*C.uchar)(&input[0]), C.int(len(input)))
-	if res != 1 {
-		return nil, fmt.Errorf("failed to decrypt [result %d]", res)
+	if res <= 0 {
+		return nil, fmt.Errorf("failed to decrypt")
 	}
 	return outbuf[:outlen], nil
 }
@@ -331,7 +328,7 @@ func (ctx *decryptionCipherCtx) DecryptUpdate(input []byte) ([]byte, error) {
 func (ctx *encryptionCipherCtx) EncryptFinal() ([]byte, error) {
 	outbuf := make([]byte, ctx.BlockSize())
 	var outlen C.int
-	if 1 != C.EVP_EncryptFinal_ex(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen) {
+	if 0 >= C.EVP_EncryptFinal_ex(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen) {
 		return nil, errors.New("encryption failed")
 	}
 	return outbuf[:outlen], nil
@@ -340,7 +337,7 @@ func (ctx *encryptionCipherCtx) EncryptFinal() ([]byte, error) {
 func (ctx *decryptionCipherCtx) DecryptFinal() ([]byte, error) {
 	outbuf := make([]byte, ctx.BlockSize())
 	var outlen C.int
-	if 1 != C.EVP_DecryptFinal_ex(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen) {
+	if 0 >= C.EVP_DecryptFinal_ex(ctx.ctx, (*C.uchar)(&outbuf[0]), &outlen) {
 		// this may mean the tag failed to verify- all previous plaintext
 		// returned must be considered faked and invalid
 		return nil, errors.New("decryption failed")
diff --git a/ciphers_gcm.go b/ciphers_gcm.go
index e21b2e5f..64daf3e7 100644
--- a/ciphers_gcm.go
+++ b/ciphers_gcm.go
@@ -88,7 +88,7 @@ func NewGCMEncryptionCipherCtx(blocksize int, e *Engine, key, iv []byte) (
 			return nil, fmt.Errorf("could not set IV len to %d: %s",
 				len(iv), err)
 		}
-		if 1 != C.EVP_EncryptInit_ex(ctx.ctx, nil, nil, nil,
+		if 0 >= C.EVP_EncryptInit_ex(ctx.ctx, nil, nil, nil,
 			(*C.uchar)(&iv[0])) {
 			return nil, errors.New("failed to apply IV")
 		}
@@ -112,7 +112,7 @@ func NewGCMDecryptionCipherCtx(blocksize int, e *Engine, key, iv []byte) (
 			return nil, fmt.Errorf("could not set IV len to %d: %s",
 				len(iv), err)
 		}
-		if 1 != C.EVP_DecryptInit_ex(ctx.ctx, nil, nil, nil,
+		if 0 >= C.EVP_DecryptInit_ex(ctx.ctx, nil, nil, nil,
 			(*C.uchar)(&iv[0])) {
 			return nil, errors.New("failed to apply IV")
 		}
@@ -125,7 +125,7 @@ func (ctx *authEncryptionCipherCtx) ExtraData(aad []byte) error {
 		return nil
 	}
 	var outlen C.int
-	if 1 != C.EVP_EncryptUpdate(ctx.ctx, nil, &outlen, (*C.uchar)(&aad[0]),
+	if 0 >= C.EVP_EncryptUpdate(ctx.ctx, nil, &outlen, (*C.uchar)(&aad[0]),
 		C.int(len(aad))) {
 		return errors.New("failed to add additional authenticated data")
 	}
@@ -137,7 +137,7 @@ func (ctx *authDecryptionCipherCtx) ExtraData(aad []byte) error {
 		return nil
 	}
 	var outlen C.int
-	if 1 != C.EVP_DecryptUpdate(ctx.ctx, nil, &outlen, (*C.uchar)(&aad[0]),
+	if 0 >= C.EVP_DecryptUpdate(ctx.ctx, nil, &outlen, (*C.uchar)(&aad[0]),
 		C.int(len(aad))) {
 		return errors.New("failed to add additional authenticated data")
 	}
diff --git a/ctx.go b/ctx.go
index 538679f5..e2830840 100644
--- a/ctx.go
+++ b/ctx.go
@@ -235,7 +235,7 @@ func (c *Ctx) SetEllipticCurve(curve EllipticCurve) error {
 	}
 	defer C.EC_KEY_free(k)
 
-	if int(C.SSL_CTX_set_tmp_ecdh_not_a_macro(c.ctx, k)) != 1 {
+	if int(C.SSL_CTX_set_tmp_ecdh_not_a_macro(c.ctx, k)) <= 0 {
 		return errorFromErrorQueue()
 	}
 
@@ -248,7 +248,7 @@ func (c *Ctx) UseCertificate(cert *Certificate) error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 	c.cert = cert
-	if int(C.SSL_CTX_use_certificate(c.ctx, cert.x)) != 1 {
+	if int(C.SSL_CTX_use_certificate(c.ctx, cert.x)) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -260,7 +260,7 @@ func (c *Ctx) AddChainCertificate(cert *Certificate) error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 	c.chain = append(c.chain, cert)
-	if int(C.SSL_CTX_add_extra_chain_cert_not_a_macro(c.ctx, cert.x)) != 1 {
+	if int(C.SSL_CTX_add_extra_chain_cert_not_a_macro(c.ctx, cert.x)) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -272,7 +272,7 @@ func (c *Ctx) UsePrivateKey(key PrivateKey) error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 	c.key = key
-	if int(C.SSL_CTX_use_PrivateKey(c.ctx, key.evpPKey())) != 1 {
+	if int(C.SSL_CTX_use_PrivateKey(c.ctx, key.evpPKey())) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -301,7 +301,7 @@ func (s *CertificateStore) AddCertificate(cert *Certificate) error {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 	s.certs = append(s.certs, cert)
-	if int(C.X509_STORE_add_cert(s.store, cert.x)) != 1 {
+	if int(C.X509_STORE_add_cert(s.store, cert.x)) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -359,7 +359,7 @@ func (c *Ctx) LoadVerifyLocations(ca_file string, ca_path string) error {
 		c_ca_path = C.CString(ca_path)
 		defer C.free(unsafe.Pointer(c_ca_path))
 	}
-	if C.SSL_CTX_load_verify_locations(c.ctx, c_ca_file, c_ca_path) != 1 {
+	if C.SSL_CTX_load_verify_locations(c.ctx, c_ca_file, c_ca_path) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -479,7 +479,7 @@ func (c *Ctx) SetSessionId(session_id []byte) error {
 		ptr = (*C.uchar)(unsafe.Pointer(&session_id[0]))
 	}
 	if int(C.SSL_CTX_set_session_id_context(c.ctx, ptr,
-		C.uint(len(session_id)))) == 0 {
+		C.uint(len(session_id)))) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
@@ -493,7 +493,7 @@ func (c *Ctx) SetCipherList(list string) error {
 	defer runtime.UnlockOSThread()
 	clist := C.CString(list)
 	defer C.free(unsafe.Pointer(clist))
-	if int(C.SSL_CTX_set_cipher_list(c.ctx, clist)) == 0 {
+	if int(C.SSL_CTX_set_cipher_list(c.ctx, clist)) <= 0 {
 		return errorFromErrorQueue()
 	}
 	return nil
diff --git a/engine.go b/engine.go
index 7a175b70..bad179c6 100644
--- a/engine.go
+++ b/engine.go
@@ -40,7 +40,7 @@ func EngineById(name string) (*Engine, error) {
 	if e.e == nil {
 		return nil, fmt.Errorf("engine %s missing", name)
 	}
-	if C.ENGINE_init(e.e) == 0 {
+	if C.ENGINE_init(e.e) <= 0 {
 		C.ENGINE_free(e.e)
 		return nil, fmt.Errorf("engine %s not initialized", name)
 	}
diff --git a/hostname.go b/hostname.go
index 4f56d640..222cd0f3 100644
--- a/hostname.go
+++ b/hostname.go
@@ -65,7 +65,7 @@ func (c *Certificate) CheckHost(host string, flags CheckFlags) error {
 	if rv > 0 {
 		return nil
 	}
-	if rv == 0 {
+	if rv <= 0 {
 		return ValidationError
 	}
 	return errors.New("hostname validation had an internal failure")
@@ -84,7 +84,7 @@ func (c *Certificate) CheckEmail(email string, flags CheckFlags) error {
 	if rv > 0 {
 		return nil
 	}
-	if rv == 0 {
+	if rv <= 0 {
 		return ValidationError
 	}
 	return errors.New("email validation had an internal failure")
@@ -102,7 +102,7 @@ func (c *Certificate) CheckIP(ip net.IP, flags CheckFlags) error {
 	if rv > 0 {
 		return nil
 	}
-	if rv == 0 {
+	if rv <= 0 {
 		return ValidationError
 	}
 	return errors.New("ip validation had an internal failure")
diff --git a/key.go b/key.go
index 2f8fc7e1..82a98378 100644
--- a/key.go
+++ b/key.go
@@ -93,18 +93,18 @@ func (key *pKey) SignPKCS1v15(method Method, data []byte) ([]byte, error) {
 	C.EVP_MD_CTX_init(&ctx)
 	defer C.EVP_MD_CTX_cleanup(&ctx)
 
-	if 1 != C.EVP_SignInit_not_a_macro(&ctx, method) {
+	if 0 >= C.EVP_SignInit_not_a_macro(&ctx, method) {
 		return nil, errors.New("signpkcs1v15: failed to init signature")
 	}
 	if len(data) > 0 {
-		if 1 != C.EVP_SignUpdate_not_a_macro(
+		if 0 >= C.EVP_SignUpdate_not_a_macro(
 			&ctx, unsafe.Pointer(&data[0]), C.uint(len(data))) {
 			return nil, errors.New("signpkcs1v15: failed to update signature")
 		}
 	}
 	sig := make([]byte, C.EVP_PKEY_size(key.key))
 	var sigblen C.uint
-	if 1 != C.EVP_SignFinal(&ctx,
+	if 0 >= C.EVP_SignFinal(&ctx,
 		((*C.uchar)(unsafe.Pointer(&sig[0]))), &sigblen, key.key) {
 		return nil, errors.New("signpkcs1v15: failed to finalize signature")
 	}
@@ -116,16 +116,16 @@ func (key *pKey) VerifyPKCS1v15(method Method, data, sig []byte) error {
 	C.EVP_MD_CTX_init(&ctx)
 	defer C.EVP_MD_CTX_cleanup(&ctx)
 
-	if 1 != C.EVP_VerifyInit_not_a_macro(&ctx, method) {
+	if 0 >= C.EVP_VerifyInit_not_a_macro(&ctx, method) {
 		return errors.New("verifypkcs1v15: failed to init verify")
 	}
 	if len(data) > 0 {
-		if 1 != C.EVP_VerifyUpdate_not_a_macro(
+		if 0 >= C.EVP_VerifyUpdate_not_a_macro(
 			&ctx, unsafe.Pointer(&data[0]), C.uint(len(data))) {
 			return errors.New("verifypkcs1v15: failed to update verify")
 		}
 	}
-	if 1 != C.EVP_VerifyFinal(&ctx,
+	if 0 >= C.EVP_VerifyFinal(&ctx,
 		((*C.uchar)(unsafe.Pointer(&sig[0]))), C.uint(len(sig)), key.key) {
 		return errors.New("verifypkcs1v15: failed to finalize verify")
 	}
@@ -145,7 +145,7 @@ func (key *pKey) MarshalPKCS1PrivateKeyPEM() (pem_block []byte,
 	}
 	defer C.RSA_free(rsa)
 	if int(C.PEM_write_bio_RSAPrivateKey(bio, rsa, nil, nil, C.int(0), nil,
-		nil)) != 1 {
+		nil)) <= 0 {
 		return nil, errors.New("failed dumping private key")
 	}
 	return ioutil.ReadAll(asAnyBio(bio))
@@ -163,7 +163,7 @@ func (key *pKey) MarshalPKCS1PrivateKeyDER() (der_block []byte,
 		return nil, errors.New("failed getting rsa key")
 	}
 	defer C.RSA_free(rsa)
-	if int(C.i2d_RSAPrivateKey_bio(bio, rsa)) != 1 {
+	if int(C.i2d_RSAPrivateKey_bio(bio, rsa)) <= 0 {
 		return nil, errors.New("failed dumping private key der")
 	}
 	return ioutil.ReadAll(asAnyBio(bio))
@@ -181,7 +181,7 @@ func (key *pKey) MarshalPKIXPublicKeyPEM() (pem_block []byte,
 		return nil, errors.New("failed getting rsa key")
 	}
 	defer C.RSA_free(rsa)
-	if int(C.PEM_write_bio_RSA_PUBKEY(bio, rsa)) != 1 {
+	if int(C.PEM_write_bio_RSA_PUBKEY(bio, rsa)) <= 0 {
 		return nil, errors.New("failed dumping public key pem")
 	}
 	return ioutil.ReadAll(asAnyBio(bio))
@@ -199,7 +199,7 @@ func (key *pKey) MarshalPKIXPublicKeyDER() (der_block []byte,
 		return nil, errors.New("failed getting rsa key")
 	}
 	defer C.RSA_free(rsa)
-	if int(C.i2d_RSA_PUBKEY_bio(bio, rsa)) != 1 {
+	if int(C.i2d_RSA_PUBKEY_bio(bio, rsa)) <= 0 {
 		return nil, errors.New("failed dumping public key der")
 	}
 	return ioutil.ReadAll(asAnyBio(bio))
@@ -228,7 +228,7 @@ func LoadPrivateKeyFromPEM(pem_block []byte) (PrivateKey, error) {
 	if key == nil {
 		return nil, errors.New("failed converting to evp_pkey")
 	}
-	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) != 1 {
+	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) <= 0 {
 		C.EVP_PKEY_free(key)
 		return nil, errors.New("failed converting to evp_pkey")
 	}
@@ -242,7 +242,7 @@ func LoadPrivateKeyFromPEM(pem_block []byte) (PrivateKey, error) {
 
 // LoadPublicKeyFromPEM loads a public key from a PEM-encoded block.
 func LoadPublicKeyFromPEM(pem_block []byte) (PublicKey, error) {
-	if len(pem_block) == 0 {
+	if len(pem_block) <= 0 {
 		return nil, errors.New("empty pem block")
 	}
 	bio := C.BIO_new_mem_buf(unsafe.Pointer(&pem_block[0]),
@@ -263,7 +263,7 @@ func LoadPublicKeyFromPEM(pem_block []byte) (PublicKey, error) {
 	if key == nil {
 		return nil, errors.New("failed converting to evp_pkey")
 	}
-	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) != 1 {
+	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) <= 0 {
 		C.EVP_PKEY_free(key)
 		return nil, errors.New("failed converting to evp_pkey")
 	}
@@ -298,7 +298,7 @@ func LoadPublicKeyFromDER(der_block []byte) (PublicKey, error) {
 	if key == nil {
 		return nil, errors.New("failed converting to evp_pkey")
 	}
-	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) != 1 {
+	if C.EVP_PKEY_set1_RSA(key, (*C.struct_rsa_st)(rsakey)) <= 0 {
 		C.EVP_PKEY_free(key)
 		return nil, errors.New("failed converting to evp_pkey")
 	}
@@ -321,7 +321,7 @@ func GenerateRSAKey(bits int) (PrivateKey, error) {
 	if key == nil {
 		return nil, errors.New("failed to allocate EVP_PKEY")
 	}
-	if C.EVP_PKEY_assign(key, C.EVP_PKEY_RSA, unsafe.Pointer(rsa)) == 0 {
+	if C.EVP_PKEY_assign(key, C.EVP_PKEY_RSA, unsafe.Pointer(rsa)) <= 0 {
 		C.EVP_PKEY_free(key)
 		return nil, errors.New("failed to assign RSA key")
 	}
diff --git a/sha1.go b/sha1.go
index 2592b662..4387ec4a 100644
--- a/sha1.go
+++ b/sha1.go
@@ -61,7 +61,7 @@ func engineRef(e *Engine) *C.ENGINE {
 }
 
 func (s *SHA1Hash) Reset() error {
-	if 1 != C.EVP_DigestInit_ex(&s.ctx, C.EVP_sha1(), engineRef(s.engine)) {
+	if 0 >= C.EVP_DigestInit_ex(&s.ctx, C.EVP_sha1(), engineRef(s.engine)) {
 		return errors.New("openssl: sha1: cannot init digest ctx")
 	}
 	return nil
@@ -71,7 +71,7 @@ func (s *SHA1Hash) Write(p []byte) (n int, err error) {
 	if len(p) == 0 {
 		return 0, nil
 	}
-	if 1 != C.EVP_DigestUpdate(&s.ctx, unsafe.Pointer(&p[0]),
+	if 0 >= C.EVP_DigestUpdate(&s.ctx, unsafe.Pointer(&p[0]),
 		C.size_t(len(p))) {
 		return 0, errors.New("openssl: sha1: cannot update digest")
 	}
@@ -79,7 +79,7 @@ func (s *SHA1Hash) Write(p []byte) (n int, err error) {
 }
 
 func (s *SHA1Hash) Sum() (result [20]byte, err error) {
-	if 1 != C.EVP_DigestFinal_ex(&s.ctx,
+	if 0 >= C.EVP_DigestFinal_ex(&s.ctx,
 		(*C.uchar)(unsafe.Pointer(&result[0])), nil) {
 		return result, errors.New("openssl: sha1: cannot finalize ctx")
 	}
diff --git a/sha256.go b/sha256.go
index 6785b32f..87f124fc 100644
--- a/sha256.go
+++ b/sha256.go
@@ -54,7 +54,7 @@ func (s *SHA256Hash) Close() {
 }
 
 func (s *SHA256Hash) Reset() error {
-	if 1 != C.EVP_DigestInit_ex(&s.ctx, C.EVP_sha256(), engineRef(s.engine)) {
+	if 0 >= C.EVP_DigestInit_ex(&s.ctx, C.EVP_sha256(), engineRef(s.engine)) {
 		return errors.New("openssl: sha256: cannot init digest ctx")
 	}
 	return nil
@@ -64,7 +64,7 @@ func (s *SHA256Hash) Write(p []byte) (n int, err error) {
 	if len(p) == 0 {
 		return 0, nil
 	}
-	if 1 != C.EVP_DigestUpdate(&s.ctx, unsafe.Pointer(&p[0]),
+	if 0 >= C.EVP_DigestUpdate(&s.ctx, unsafe.Pointer(&p[0]),
 		C.size_t(len(p))) {
 		return 0, errors.New("openssl: sha256: cannot update digest")
 	}
@@ -72,7 +72,7 @@ func (s *SHA256Hash) Write(p []byte) (n int, err error) {
 }
 
 func (s *SHA256Hash) Sum() (result [32]byte, err error) {
-	if 1 != C.EVP_DigestFinal_ex(&s.ctx,
+	if 0 >= C.EVP_DigestFinal_ex(&s.ctx,
 		(*C.uchar)(unsafe.Pointer(&result[0])), nil) {
 		return result, errors.New("openssl: sha256: cannot finalize ctx")
 	}