diff --git a/library/cmac.c b/library/cmac.c
index 5575d5c..d3581d5 100644
--- a/library/cmac.c
+++ b/library/cmac.c
@@ -65,7 +65,7 @@
 #endif /* MBEDTLS_SELF_TEST */
 #endif /* MBEDTLS_PLATFORM_C */
 
-#if !defined(MBEDTLS_CMAC_ALT)
+#if !defined(MBEDTLS_CMAC_ALT) || defined(MBEDTLS_SELF_TEST)
 
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
@@ -166,7 +166,9 @@
 
     return( ret );
 }
+#endif /* !defined(MBEDTLS_CMAC_ALT) || defined(MBEDTLS_SELF_TEST) */
 
+#if !defined(MBEDTLS_CMAC_ALT)
 static void cmac_xor_block( unsigned char *output, const unsigned char *input1,
                             const unsigned char *input2,
                             const size_t block_size )