diff --git a/include/mbedtls/constant_time.h b/include/mbedtls/constant_time.h
index bd7758f..b7f9a86 100644
--- a/include/mbedtls/constant_time.h
+++ b/include/mbedtls/constant_time.h
@@ -38,7 +38,7 @@
  * \return      Zero if the content of the two buffer is the same,
  *              otherwise non-zero.
  */
-int mbedtls_cf_memcmp( const void *a,
+int mbedtls_ct_memcmp( const void *a,
                        const void *b,
                        size_t n );