diff --git a/macro/src/expand.rs b/macro/src/expand.rs
index 1896a13..16dab26 100644
--- a/macro/src/expand.rs
+++ b/macro/src/expand.rs
@@ -233,21 +233,17 @@
     let args = efn.args.iter().map(|arg| expand_extern_arg(arg, types));
     let vars = efn.args.iter().map(|arg| {
         let ident = &arg.ident;
-        let var = if types.needs_indirect_abi(&arg.ty) {
-            quote!(::std::ptr::read(#ident))
-        } else {
-            quote!(#ident)
-        };
         match &arg.ty {
-            Type::Ident(ident) if ident == "String" => quote!(#var.into_string()),
-            Type::RustBox(_) => quote!(::std::boxed::Box::from_raw(#var)),
-            Type::UniquePtr(_) => quote!(::cxx::UniquePtr::from_raw(#var)),
+            Type::Ident(i) if i == "String" => quote!(::std::mem::take((*#ident).as_mut_string())),
+            Type::RustBox(_) => quote!(::std::boxed::Box::from_raw(#ident)),
+            Type::UniquePtr(_) => quote!(::cxx::UniquePtr::from_raw(#ident)),
             Type::Ref(ty) => match &ty.inner {
-                Type::Ident(ident) if ident == "String" => quote!(#var.as_string()),
-                _ => var,
+                Type::Ident(i) if i == "String" => quote!(#ident.as_string()),
+                _ => quote!(#ident),
             },
-            Type::Str(_) => quote!(#var.as_str()),
-            _ => var,
+            Type::Str(_) => quote!(#ident.as_str()),
+            ty if types.needs_indirect_abi(ty) => quote!(::std::ptr::read(#ident)),
+            _ => quote!(#ident),
         }
     });
     let mut outparam = None;