diff --git a/library/x509.c b/library/x509.c
index a796760..1e61db8 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -588,9 +588,8 @@
         if( ret != 0 )
             goto exit;
 
-        // use regular memcmp as oid is not that critical
         if( oid[0].len != oid[1].len ||
-            memcmp( oid[0].p, oid[1].p, oid[1].len ) != 0 )
+            mbedtls_platform_memcmp( oid[0].p, oid[1].p, oid[1].len ) != 0 )
         {
             return( 1 );
         }