diff --git a/aleksis/core/schema/base.py b/aleksis/core/schema/base.py
index 797757d7d3be427b62544b94357488de8b2f825a..302450498728a3435615fb8821fde09a80b3a81b 100644
--- a/aleksis/core/schema/base.py
+++ b/aleksis/core/schema/base.py
@@ -84,7 +84,7 @@ class OptimisticResponseTypeMixin:
     but should be set to true by the frontend
     """
 
-    is_optimistic = graphene.Boolean(default=False)
+    is_optimistic = graphene.Boolean(default_value=False)
 
 
 class PermissionBatchPatchMixin: