diff --git a/transformations/SimplifyProcs.hs b/transformations/SimplifyProcs.hs
index e89e16a..64e9168 100644
--- a/transformations/SimplifyProcs.hs
+++ b/transformations/SimplifyProcs.hs
@@ -33,7 +33,7 @@ simplifyProcs :: [Pass]
 simplifyProcs = makePassesDep
       [ ("Wrap PAR subprocesses in PROCs", parsToProcs, [Prop.parUsageChecked], [Prop.parsWrapped])
       , ("Remove parallel assignment", removeParAssign, [Prop.parUsageChecked, Prop.functionsRemoved], [Prop.assignParRemoved])
-      , ("Flatten assignment", flattenAssign, [Prop.assignParRemoved], [Prop.assignFlattened])
+      , ("Flatten assignment", flattenAssign, Prop.agg_typesDone ++ [Prop.assignParRemoved], [Prop.assignFlattened])
       ]
 
 -- | Wrap the subprocesses of PARs in no-arg PROCs.