diff --git a/apps/common/tree.py b/apps/common/tree.py
index a9da1482f..1ffe4347e 100644
--- a/apps/common/tree.py
+++ b/apps/common/tree.py
@@ -51,7 +51,7 @@ class TreeNode:
             result = True
         elif self.pId != other.pId:
             result = self.pId > other.pId
-        elif self.id.startswith('-') and not other.id.startswith('-'):
+        elif str(self.id).startswith('-') and not str(other.id).startswith('-'):
             result = False
         else:
             result = self.name > other.name