diff --git a/libyul/Object.cpp b/libyul/Object.cpp
index 7833ba759..e357e1561 100644
--- a/libyul/Object.cpp
+++ b/libyul/Object.cpp
@@ -145,7 +145,11 @@ set<YulString> Object::qualifiedDataNames() const
 	return qualifiedNames;
 }
 
-void Object::traverseObjectTree(Object const* _object, YulString _qualifiedName, std::function<bool(Object const*)> _visitor)
+void Object::traverseObjectTree(
+	Object const* _object,
+	YulString _qualifiedName,
+	std::function<bool(Object const*)> const& _visitor
+)
 {
 	yulAssert(!_qualifiedName.empty(), "");
 
diff --git a/libyul/Object.h b/libyul/Object.h
index d37d6c70b..131b2b5d5 100644
--- a/libyul/Object.h
+++ b/libyul/Object.h
@@ -122,7 +122,7 @@ public:
 	static void traverseObjectTree(
 		Object const* _object,
 		YulString _qualifiedName,
-		std::function<bool(Object const*)> _visitor
+		std::function<bool(Object const*)> const& _visitor
 	);
 
 	/// sub id for object if it is subobject of another object, max value if it is not subobject