diff --git a/wcs/workflows.py b/wcs/workflows.py
index ef59cdb7c..ef97419e3 100644
--- a/wcs/workflows.py
+++ b/wcs/workflows.py
@@ -1673,8 +1673,8 @@ class WorkflowStatus(object):
             if not action.identifier:
                 continue
             roles = action.by
-            functions = [x for x in roles if x in self.parent.roles]
-            roles = [x for x in roles if x not in self.parent.roles]
+            functions = [x for x in roles if x in (self.parent.roles or [])]
+            roles = [x for x in roles if x not in (self.parent.roles or [])]
             if functions or roles:
                 actions.append({'action': StatusAction(action), 'roles': roles, 'functions': functions})
         return actions