diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index 4786aacaf..037fdb3b2 100644
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -625,6 +625,9 @@ struct HierarchyPass : public Pass {
 			for (auto module : design->modules())
 			for (auto cell : module->cells())
 			{
+				if (GetSize(cell->parameters) != 0)
+					continue;
+
 				Module *m = design->module(cell->type);
 
 				if (m == nullptr)