diff --git a/src/dzitilesource.js b/src/dzitilesource.js
index 6c95dbee..54b8cb68 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 fe4677a0..e7eb2114 100644
--- a/test/modules/dzitilesource.js
+++ b/test/modules/dzitilesource.js
@@ -32,7 +32,10 @@
             'relative link should stay the same');
         testImplicitTilesUrl(
             '/p/foo.dzi?a=1&b=2', '/p/foo_files/',
-            'querystring in dzi url should be ignored');
+            'querystring in dzi url should be ignored after slashes');
+        testImplicitTilesUrl(
+                '/iiipsrv?DeepZoom=/path/my.dzi', '/iiipsrv?DeepZoom=/path/my_files/',
+                'querystring in dzi url should not be ignored before slashes');
     });
 
 }());