diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index dfb1541..58a5d63 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -62,6 +62,8 @@
 #define MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED  -0x6280  /**< Decryption of block requires a full block. */
 #define MBEDTLS_ERR_CIPHER_AUTH_FAILED          -0x6300  /**< Authentication failed (for AEAD modes). */
 #define MBEDTLS_ERR_CIPHER_INVALID_CONTEXT      -0x6380  /**< The context is invalid. For example, because it was freed. */
+
+/* MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED is deprecated and should not be used. */
 #define MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED      -0x6400  /**< Cipher hardware accelerator failed. */
 
 #define MBEDTLS_CIPHER_VARIABLE_IV_LEN     0x01    /**< Cipher accepts IVs of variable length. */