diff --git a/lang/types/type.go b/lang/types/type.go
index 9461b1f9..aa72ca86 100644
--- a/lang/types/type.go
+++ b/lang/types/type.go
@@ -550,8 +550,12 @@ func NewType(s string) *Type {
 	return nil // error (this also matches the empty string as input)
 }
 
-// New creates a new Value of this type.
+// New creates a new Value of this type. It will represent the "zero" value. It
+// panics if you give it a malformed type.
 func (obj *Type) New() Value {
+	if obj == nil {
+		panic("malformed type")
+	}
 	switch obj.Kind {
 	case KindBool:
 		return NewBool()
diff --git a/lang/types/value.go b/lang/types/value.go
index 9281d974..1edd23e9 100644
--- a/lang/types/value.go
+++ b/lang/types/value.go
@@ -774,6 +774,7 @@ func NewList(t *Type) *ListValue {
 		return nil // sanity check
 	}
 	return &ListValue{
+		V: []Value{},
 		T: t,
 	}
 }