diff --git a/library/x509_crl.c b/library/x509_crl.c
index 3113de4..7f99683 100644
--- a/library/x509_crl.c
+++ b/library/x509_crl.c
@@ -511,10 +511,10 @@
     }
 
     if( crl->sig_oid.len != sig_oid2.len ||
-        memcmp( crl->sig_oid.p, sig_oid2.p, crl->sig_oid.len ) != 0 ||
+        mbedtls_platform_memcmp( crl->sig_oid.p, sig_oid2.p, crl->sig_oid.len ) != 0 ||
         sig_params1.len != sig_params2.len ||
         ( sig_params1.len != 0 &&
-          memcmp( sig_params1.p, sig_params2.p, sig_params1.len ) != 0 ) )
+          mbedtls_platform_memcmp( sig_params1.p, sig_params2.p, sig_params1.len ) != 0 ) )
     {
         mbedtls_x509_crl_free( crl );
         return( MBEDTLS_ERR_X509_SIG_MISMATCH );