diff --git a/src/Controller/AdminController.php b/src/Controller/AdminController.php
index 06393cb..d888bd8 100644
--- a/src/Controller/AdminController.php
+++ b/src/Controller/AdminController.php
@@ -116,7 +116,7 @@ public function favoriteOutputDefinitionsAction(Request $request)
         $list = new FavoriteOutputDefinition\Listing();
         $list->setOrder('asc');
         $list->setOrderKey('description');
-        $condition = 'o_classId = ' . $request->get('classId');
+        $condition = 'o_classId = ' . $list->quote($request->get('classId'));
         $list->setCondition($condition);
 
         $definitions = [];