diff --git a/lib/types/string.js b/lib/types/string.js
index d472e610..c5fcec55 100755
--- a/lib/types/string.js
+++ b/lib/types/string.js
@@ -742,7 +742,8 @@ module.exports = Any.extend({
 internals.addressOptions = function (options) {
 
     if (!options) {
-        return options;
+        assert(internals.tlds, 'Built-in TLD list disabled');
+        return Object.assign({}, options, internals.tlds);
     }
 
     // minDomainSegments