diff --git a/library/oid.c b/library/oid.c
index abe7bc7..00a02c3 100644
--- a/library/oid.c
+++ b/library/oid.c
@@ -75,7 +75,7 @@
         if( p == NULL || oid == NULL ) return( NULL );                  \
         while( cur->asn1 != NULL ) {                                    \
             if( cur->asn1_len == oid->len &&                            \
-                memcmp( cur->asn1, oid->p, oid->len ) == 0 ) {          \
+                mbedtls_platform_memcmp( cur->asn1, oid->p, oid->len ) == 0 ) {          \
                 return( p );                                            \
             }                                                           \
             p++;                                                        \