diff --git a/passes/opt/opt_merge.cc b/passes/opt/opt_merge.cc
index 07e4dd39f..b63fd3c8d 100644
--- a/passes/opt/opt_merge.cc
+++ b/passes/opt/opt_merge.cc
@@ -275,6 +275,9 @@ struct OptMergeWorker
 			ct.cell_types.erase("$pmux");
 		}
 
+		ct.cell_types.erase("$anyseq");
+		ct.cell_types.erase("$anyconst");
+
 		log("Finding identical cells in module `%s'.\n", module->name.c_str());
 		assign_map.set(module);