diff --git a/src/ltlvisit/simplify.cc b/src/ltlvisit/simplify.cc
index 31238fe58..af393a40f 100644
--- a/src/ltlvisit/simplify.cc
+++ b/src/ltlvisit/simplify.cc
@@ -2367,9 +2367,9 @@ namespace spot
 	}
 
 	void
-	visit(const automatop*)
+	visit(const automatop* aut)
 	{
-	  assert(0);
+	  result_ = aut->clone();
 	}
 
 	void