diff --git a/codegen/src/function.rs b/codegen/src/function.rs
index 2c0cf525..2fca6d96 100644
--- a/codegen/src/function.rs
+++ b/codegen/src/function.rs
@@ -666,8 +666,7 @@ impl ExportedFn {
                             is_string = true;
                             is_ref = false;
                             quote_spanned!(arg_type.span()=>
-                                                   mem::take(args[#i])
-                                                   .clone().cast::<#arg_type>())
+                                           mem::take(args[#i]).take_string().unwrap())
                         }
                         _ => {
                             is_string = false;