diff --git a/taiga/permissions/services.py b/taiga/permissions/services.py
index 8cb679a1..32357926 100644
--- a/taiga/permissions/services.py
+++ b/taiga/permissions/services.py
@@ -51,7 +51,7 @@ def is_project_owner(user, obj):
     if project is None:
         return False
 
-    if user.id == project.owner.id:
+    if user.id == project.owner_id:
         return True
 
     return False