diff --git a/test/Model/Types/WorkflowSpec.hs b/test/Model/Types/WorkflowSpec.hs
index d43af9ae8..835c5ad42 100644
--- a/test/Model/Types/WorkflowSpec.hs
+++ b/test/Model/Types/WorkflowSpec.hs
@@ -47,6 +47,9 @@ instance (Arbitrary fileid, Arbitrary userid, Typeable fileid, Typeable userid,
 instance Arbitrary WorkflowPayloadTextPreset where
   arbitrary = genericArbitrary
   shrink = genericShrink
+instance Arbitrary WorkflowPayloadTextType where
+  arbitrary = genericArbitrary
+  shrink = genericShrink
 instance Arbitrary (WorkflowPayloadField fileid userid Text) where
   arbitrary = WorkflowPayloadFieldText
     <$> scale (`div` 2) arbitrary