diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index 5b590db..f2d3ede 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -229,7 +229,7 @@
     if( ret != 0 )
         return( ret );
 
-    if( mbedtls_platform_memcmp( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 )
+    if( mbedtls_platform_memequal( cookie + 4, ref_hmac, sizeof( ref_hmac ) ) != 0 )
         return( -1 );
 
 #if defined(MBEDTLS_HAVE_TIME)