diff --git a/hilti/toolchain/src/compiler/visitors/normalizer.cc b/hilti/toolchain/src/compiler/visitors/normalizer.cc
index bb2c0e439..5a1959ecf 100644
--- a/hilti/toolchain/src/compiler/visitors/normalizer.cc
+++ b/hilti/toolchain/src/compiler/visitors/normalizer.cc
@@ -64,8 +64,8 @@ struct VisitorNormalizer : public visitor::PreOrder<void, VisitorNormalizer> {
 
     // Helper to replace an type constructor expression that receives a
     // constant argument with a corresponding ctor expression.
-    template<typename Ctor, typename Operator>
-    void tryReplaceCtorExpression(const Operator& op, position_t p, std::function<hilti::Ctor(const Ctor& ctor)> cb) {
+    template<typename Ctor, typename Operator, typename Fn>
+    void tryReplaceCtorExpression(const Operator& op, position_t p, Fn ctor)> cb) {
         if ( auto ctor = detail::foldConstant<Ctor>(callArgument(op, 0)) ) {
             try {
                 auto i = cb(*ctor);