diff --git a/src/js/static-net-filtering.js b/src/js/static-net-filtering.js
index db6361a30..261cc8621 100644
--- a/src/js/static-net-filtering.js
+++ b/src/js/static-net-filtering.js
@@ -2271,7 +2271,7 @@ FilterContainer.prototype.fromCompiledContent = function(reader) {
 /******************************************************************************/
 
 FilterContainer.prototype.matchAndFetchData = function(dataType, requestURL, out, outlog) {
-    if ( this.dataFilters.length === 0 ) { return; }
+    if ( this.dataFilters.size === 0 ) { return; }
 
     let url = this.urlTokenizer.setURL(requestURL);