diff --git a/storyboard/api/v1/wmodels.py b/storyboard/api/v1/wmodels.py
index 3b785eca..af7ea2de 100644
--- a/storyboard/api/v1/wmodels.py
+++ b/storyboard/api/v1/wmodels.py
@@ -558,7 +558,8 @@ class WorklistFilter(base.APIBase):
     list_id = int
     """The ID of the Worklist this filter is for."""
 
-    filter_criteria = wtypes.ArrayType(FilterCriterion)
+    filter_criteria = wtypes.wsattr(wtypes.ArrayType(FilterCriterion),
+                                    mandatory=True)
     """The list of criteria to apply."""
 
     @nodoc