diff --git a/ext/openssl/ossl.c b/ext/openssl/ossl.c
index b9e5ba2a98..b64f1e0e34 100644
--- a/ext/openssl/ossl.c
+++ b/ext/openssl/ossl.c
@@ -667,7 +667,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  * ahold of the key may use it unless it is encrypted.  In order to securely
  * export a key you may export it with a pass phrase.
  *
- *   cipher = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   cipher = OpenSSL::Cipher.new 'aes-256-cbc'
  *   pass_phrase = 'my secure pass phrase goes here'
  *
  *   key_secure = key.export cipher, pass_phrase
@@ -775,7 +775,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  * using PBKDF2. PKCS #5 v2.0 recommends at least 8 bytes for the salt,
  * the number of iterations largely depends on the hardware being used.
  *
- *   cipher = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   cipher = OpenSSL::Cipher.new 'aes-256-cbc'
  *   cipher.encrypt
  *   iv = cipher.random_iv
  *
@@ -798,7 +798,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  * Use the same steps as before to derive the symmetric AES key, this time
  * setting the Cipher up for decryption.
  *
- *   cipher = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   cipher = OpenSSL::Cipher.new 'aes-256-cbc'
  *   cipher.decrypt
  *   cipher.iv = iv # the one generated with #random_iv
  *
@@ -833,7 +833,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  *
  * First set up the cipher for encryption
  *
- *   encryptor = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   encryptor = OpenSSL::Cipher.new 'aes-256-cbc'
  *   encryptor.encrypt
  *   encryptor.pkcs5_keyivgen pass_phrase, salt
  *
@@ -846,7 +846,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  *
  * Use a new Cipher instance set up for decryption
  *
- *   decryptor = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   decryptor = OpenSSL::Cipher.new 'aes-256-cbc'
  *   decryptor.decrypt
  *   decryptor.pkcs5_keyivgen pass_phrase, salt
  *
@@ -934,7 +934,7 @@ ossl_crypto_fixed_length_secure_compare(VALUE dummy, VALUE str1, VALUE str2)
  *   ca_key = OpenSSL::PKey::RSA.new 2048
  *   pass_phrase = 'my secure pass phrase goes here'
  *
- *   cipher = OpenSSL::Cipher.new 'AES-256-CBC'
+ *   cipher = OpenSSL::Cipher.new 'aes-256-cbc'
  *
  *   open 'ca_key.pem', 'w', 0400 do |io|
  *     io.write ca_key.export(cipher, pass_phrase)
diff --git a/ext/openssl/ossl_cipher.c b/ext/openssl/ossl_cipher.c
index 5b92fc39f0..28f5c1b5ef 100644
--- a/ext/openssl/ossl_cipher.c
+++ b/ext/openssl/ossl_cipher.c
@@ -104,7 +104,7 @@ ossl_cipher_alloc(VALUE klass)
  *  call-seq:
  *     Cipher.new(string) -> cipher
  *
- *  The string must contain a valid cipher name like "AES-256-CBC".
+ *  The string must contain a valid cipher name like "aes-256-cbc".
  *
  *  A list of cipher names is available by calling OpenSSL::Cipher.ciphers.
  */
@@ -874,7 +874,7 @@ Init_ossl_cipher(void)
      * individual components name, key length and mode. Either all uppercase
      * or all lowercase strings may be used, for example:
      *
-     *  cipher = OpenSSL::Cipher.new('AES-128-CBC')
+     *  cipher = OpenSSL::Cipher.new('aes-128-cbc')
      *
      * === Choosing either encryption or decryption mode
      *
@@ -904,7 +904,7 @@ Init_ossl_cipher(void)
      * without processing the password further. A simple and secure way to
      * create a key for a particular Cipher is
      *
-     *  cipher = OpenSSL::Cipher.new('AES-256-CFB')
+     *  cipher = OpenSSL::Cipher.new('aes-256-cfb')
      *  cipher.encrypt
      *  key = cipher.random_key # also sets the generated key on the Cipher
      *
@@ -972,14 +972,14 @@ Init_ossl_cipher(void)
      *
      *   data = "Very, very confidential data"
      *
-     *   cipher = OpenSSL::Cipher.new('AES-128-CBC')
+     *   cipher = OpenSSL::Cipher.new('aes-128-cbc')
      *   cipher.encrypt
      *   key = cipher.random_key
      *   iv = cipher.random_iv
      *
      *   encrypted = cipher.update(data) + cipher.final
      *   ...
-     *   decipher = OpenSSL::Cipher.new('AES-128-CBC')
+     *   decipher = OpenSSL::Cipher.new('aes-128-cbc')
      *   decipher.decrypt
      *   decipher.key = key
      *   decipher.iv = iv
@@ -1015,7 +1015,7 @@ Init_ossl_cipher(void)
      * not to reuse the _key_ and _nonce_ pair. Reusing an nonce ruins the
      * security guarantees of GCM mode.
      *
-     *   cipher = OpenSSL::Cipher.new('AES-128-GCM').encrypt
+     *   cipher = OpenSSL::Cipher.new('aes-128-gcm').encrypt
      *   cipher.key = key
      *   cipher.iv = nonce
      *   cipher.auth_data = auth_data
@@ -1031,7 +1031,7 @@ Init_ossl_cipher(void)
      * ciphertext with a probability of 1/256.
      *
      *   raise "tag is truncated!" unless tag.bytesize == 16
-     *   decipher = OpenSSL::Cipher.new('AES-128-GCM').decrypt
+     *   decipher = OpenSSL::Cipher.new('aes-128-gcm').decrypt
      *   decipher.key = key
      *   decipher.iv = nonce
      *   decipher.auth_tag = tag
diff --git a/test/openssl/test_cipher.rb b/test/openssl/test_cipher.rb
index 65b36dd180..45ec94a7d6 100644
--- a/test/openssl/test_cipher.rb
+++ b/test/openssl/test_cipher.rb
@@ -147,13 +147,13 @@ class OpenSSL::TestCipher < OpenSSL::TestCase
 
   def test_AES
     pt = File.read(__FILE__)
-    %w(ECB CBC CFB OFB).each{|mode|
-      c1 = OpenSSL::Cipher.new("AES-256-#{mode}")
+    %w(ecb cbc cfb ofb).each{|mode|
+      c1 = OpenSSL::Cipher.new("aes-256-#{mode}")
       c1.encrypt
       c1.pkcs5_keyivgen("passwd")
       ct = c1.update(pt) + c1.final
 
-      c2 = OpenSSL::Cipher.new("AES-256-#{mode}")
+      c2 = OpenSSL::Cipher.new("aes-256-#{mode}")
       c2.decrypt
       c2.pkcs5_keyivgen("passwd")
       assert_equal(pt, c2.update(ct) + c2.final)
@@ -163,7 +163,7 @@ class OpenSSL::TestCipher < OpenSSL::TestCase
   def test_update_raise_if_key_not_set
     assert_raise(OpenSSL::Cipher::CipherError) do
       # it caused OpenSSL SEGV by uninitialized key [Bug #2768]
-      OpenSSL::Cipher.new("AES-128-ECB").update "." * 17
+      OpenSSL::Cipher.new("aes-128-ecb").update "." * 17
     end
   end