diff --git a/gns3server/controller/gns3vm/__init__.py b/gns3server/controller/gns3vm/__init__.py
index 795e15a8..6a745d15 100644
--- a/gns3server/controller/gns3vm/__init__.py
+++ b/gns3server/controller/gns3vm/__init__.py
@@ -250,6 +250,7 @@ class GNS3VM:
     def __json__(self):
         return self._settings
 
+    @locking
     async def list(self, engine):
         """
         List VMS for an engine