Index: lib/filterClasses.js
===================================================================
--- a/lib/filterClasses.js
+++ b/lib/filterClasses.js
@@ -300,17 +300,18 @@
  *   e.g. "foo.com|bar.com|~baz.com"
  * @constructor
  * @augments Filter
  */
 function ActiveFilter(text, domains)
 {
   Filter.call(this, text);
 
-  this.domainSource = domains;
+  if (domains)
+    this.domainSource = domains;
 }
 exports.ActiveFilter = ActiveFilter;
 
 ActiveFilter.prototype = extend(Filter, {
   _disabled: false,
   _hitCount: 0,
   _lastHit: 0,