diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index a133ed9..0455efe 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -275,8 +275,8 @@
     /** Name of the cipher. */
     const char *MBEDTLS_PRIVATE(name);
 
-    /** Struct for base cipher information and functions. */
-    const mbedtls_cipher_base_t *MBEDTLS_PRIVATE(base);
+    /** Index to LUT for base cipher information and functions. */
+    uint8_t MBEDTLS_PRIVATE(base_idx) : 5;
 
     /** Full cipher identifier. For example,
      * MBEDTLS_CIPHER_AES_256_CBC.