diff --git a/lang/funcs/collection.go b/lang/funcs/collection.go
index 264ed122d..cf0958f44 100644
--- a/lang/funcs/collection.go
+++ b/lang/funcs/collection.go
@@ -516,7 +516,7 @@ var LookupFunc = function.New(&function.Spec{
 		switch {
 		case ty.IsObjectType():
 			if !args[1].IsKnown() {
-				return args[2].Type(), nil
+				return cty.DynamicPseudoType, nil
 			}
 
 			key := args[1].AsString()