diff --git a/src/Expr.cc b/src/Expr.cc
index 96bbefaa76..bf68c7bc40 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -5029,7 +5029,7 @@ bool ListExpr::IsPure() const
 
 ValPtr ListExpr::Eval(Frame* f) const
 	{
-	auto v = make_intrusive<ListVal>(TYPE_ANY);
+	std::vector<ValPtr> evs;
 
 	for ( const auto& expr : exprs )
 		{
@@ -5041,10 +5041,10 @@ ValPtr ListExpr::Eval(Frame* f) const
 			return nullptr;
 			}
 
-		v->Append(std::move(ev));
+		evs.push_back(std::move(ev));
 		}
 
-	return v;
+	return make_intrusive<ListVal>(cast_intrusive<TypeList>(type), std::move(evs));
 	}
 
 TypePtr ListExpr::InitType() const
diff --git a/src/Val.cc b/src/Val.cc
index d95e217fc6..d8edeb532f 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -1563,6 +1563,12 @@ ListVal::ListVal(TypeTag t) : Val(make_intrusive<TypeList>(t == TYPE_ANY ? nullp
 	tag = t;
 	}
 
+ListVal::ListVal(TypeListPtr tl, std::vector<ValPtr> _vals) : Val(std::move(tl))
+	{
+	tag = TYPE_ANY;
+	vals = std::move(_vals);
+	}
+
 ValPtr ListVal::SizeVal() const
 	{
 	return val_mgr->Count(vals.size());
diff --git a/src/Val.h b/src/Val.h
index 71b4eee1b4..fc891aa7dc 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -661,8 +661,15 @@ private:
 class ListVal final : public Val
 	{
 public:
+	// Constructor used to build up a homogeneous list of values;
+	// or, if 't' is TYPE_ANY, then a heterogeneous one whose type
+	// is built up as values are appended.
 	explicit ListVal(TypeTag t);
 
+	// Constructor used to build the list in one shot, with the type
+	// pre-computed.
+	ListVal(TypeListPtr tl, std::vector<ValPtr> vals);
+
 	~ListVal() override = default;
 
 	TypeTag BaseTag() const { return tag; }