diff --git a/include/openssl/cipher.h b/include/openssl/cipher.h
index 727d7a7..b8d4e52 100644
--- a/include/openssl/cipher.h
+++ b/include/openssl/cipher.h
@@ -438,7 +438,7 @@
 // EVP_CIPH_NO_PADDING disables padding in block ciphers.
 #define EVP_CIPH_NO_PADDING 0x800
 
-// EVP_CIPHER_CTX_ctrl commands.
+// The following are |EVP_CIPHER_CTX_ctrl| commands.
 #define EVP_CTRL_INIT 0x0
 #define EVP_CTRL_SET_KEY_LENGTH 0x1
 #define EVP_CTRL_GET_RC2_KEY_BITS 0x2
@@ -454,15 +454,12 @@
 #define EVP_CTRL_AEAD_SET_IV_FIXED 0x12
 #define EVP_CTRL_GCM_IV_GEN 0x13
 #define EVP_CTRL_AEAD_SET_MAC_KEY 0x17
-// Set the GCM invocation field, decrypt only
+// EVP_CTRL_GCM_SET_IV_INV sets the GCM invocation field, decrypt only
 #define EVP_CTRL_GCM_SET_IV_INV 0x18
 
-// GCM TLS constants
-// Length of fixed part of IV derived from PRF
+// The following constants are unused.
 #define EVP_GCM_TLS_FIXED_IV_LEN 4
-// Length of explicit part of IV part of TLS records
 #define EVP_GCM_TLS_EXPLICIT_IV_LEN 8
-// Length of tag for TLS
 #define EVP_GCM_TLS_TAG_LEN 16
 
 // The following are legacy aliases for AEAD |EVP_CIPHER_CTX_ctrl| values.