diff --git a/src/dzitilesource.js b/src/dzitilesource.js
index 54b8cb68..443bfaca 100644
--- a/src/dzitilesource.js
+++ b/src/dzitilesource.js
@@ -140,7 +140,7 @@ $.extend( $.DziTileSource.prototype, $.TileSource.prototype, /** @lends OpenSead
 
         if (url && !options.tilesUrl) {
             options.tilesUrl = url.replace(
-                    /([^\/]+?)(\.(dzi|xml|js))?(\?[^\/]*)?\/?$/, '$1_files/');
+                    /([^\/]+?)(\.(dzi|xml|js)?(\?[^\/]*)?)?\/?$/, '$1_files/');
 
             if (url.search(/\.(dzi|xml|js)\?/) != -1) {
                 options.queryParams = url.match(/\?.*/);
diff --git a/test/modules/dzitilesource.js b/test/modules/dzitilesource.js
index e7eb2114..25b0c265 100644
--- a/test/modules/dzitilesource.js
+++ b/test/modules/dzitilesource.js
@@ -36,6 +36,9 @@
         testImplicitTilesUrl(
                 '/iiipsrv?DeepZoom=/path/my.dzi', '/iiipsrv?DeepZoom=/path/my_files/',
                 'querystring in dzi url should not be ignored before slashes');
+        testImplicitTilesUrl(
+                '/fcg-bin/iipsrv.fcgi?Deepzoom=123test.tif.dzi', '/fcg-bin/iipsrv.fcgi?Deepzoom=123test.tif_files/',
+                'filename in querystring does not have to contain slash');
     });
 
 }());