diff --git a/include/mbedtls/cipher_internal.h b/include/mbedtls/cipher_internal.h
index 9cab3bb..587e3ea 100644
--- a/include/mbedtls/cipher_internal.h
+++ b/include/mbedtls/cipher_internal.h
@@ -79,11 +79,11 @@
 
     /** Set key for encryption purposes */
     int (*setkey_enc_func)( void *ctx, const unsigned char *key,
-                            unsigned int key_length );
+                            unsigned int key_bitlen );
 
     /** Set key for decryption purposes */
     int (*setkey_dec_func)( void *ctx, const unsigned char *key,
-                            unsigned int key_length);
+                            unsigned int key_bitlen);
 
     /** Allocate a new context */
     void * (*ctx_alloc_func)( void );