diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 2345944..8498090 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -256,16 +256,15 @@
     }
 
     if (element_settings.dialogType) {
-      var query_parameters_prefix = '';
       // Ensure that we have a valid URL by adding ? when no query parameter is
       // yet available, otherwise append using &.
       if (ajax.options.url.indexOf('?') === -1) {
-        query_parameters_prefix = '?';
+        ajax.options.url += '?';
       }
       else {
-        query_parameters_prefix = '&';
+        ajax.options.url += '&';
       }
-      ajax.options.url += query_parameters_prefix + 'dialogType=' + element_settings.dialogType;
+      ajax.options.url += 'dialogType=' + element_settings.dialogType;
     }
 
     // Bind the ajaxSubmit function to the element event.