diff --git a/rustler_codegen/src/nif.rs b/rustler_codegen/src/nif.rs
index ffee4c94..f7d65256 100644
--- a/rustler_codegen/src/nif.rs
+++ b/rustler_codegen/src/nif.rs
@@ -48,8 +48,12 @@ pub fn transcoder_decorator(nif_attributes: NifAttributes, fun: syn::ItemFn) ->
     let argument_names = create_function_params(inputs.clone());
     let erl_func_name = nif_attributes
         .custom_name
-        .map(|n| syn::Ident::new(n.value().as_str(), Span::call_site()))
-        .unwrap_or_else(|| name.clone());
+        .map(|n| n.value().to_string())
+        .unwrap_or_else(|| name.clone().to_string());
+
+    if !erl_func_name.is_ascii() {
+        panic!("Only ASCII strings are supported as function names");
+    }
 
     quote! {
         #[allow(non_camel_case_types)]
diff --git a/rustler_tests/lib/rustler_test.ex b/rustler_tests/lib/rustler_test.ex
index 1adaded7..ce424d40 100644
--- a/rustler_tests/lib/rustler_test.ex
+++ b/rustler_tests/lib/rustler_test.ex
@@ -121,7 +121,7 @@ defmodule RustlerTest do
   def raise_term_with_atom_error(), do: err()
   def term_with_tuple_error(), do: err()
 
-  def nif_attrs_can_rename(), do: err()
+  def nif_attrs_can_rename!(), do: err()
 
   def add_from_tuple(_tuple), do: err()
   def add_one_to_tuple(_tuple), do: err()
diff --git a/rustler_tests/native/rustler_test/src/test_nif_attrs.rs b/rustler_tests/native/rustler_test/src/test_nif_attrs.rs
index 1c40c22c..e992d0b8 100644
--- a/rustler_tests/native/rustler_test/src/test_nif_attrs.rs
+++ b/rustler_tests/native/rustler_test/src/test_nif_attrs.rs
@@ -1,4 +1,4 @@
-#[rustler::nif(name = "nif_attrs_can_rename")]
+#[rustler::nif(name = "nif_attrs_can_rename!")]
 pub fn can_rename() -> bool {
     true
 }
diff --git a/rustler_tests/test/nif_attrs_test.exs b/rustler_tests/test/nif_attrs_test.exs
index 1e916c91..6805436e 100644
--- a/rustler_tests/test/nif_attrs_test.exs
+++ b/rustler_tests/test/nif_attrs_test.exs
@@ -2,6 +2,6 @@ defmodule NifAttrsTest do
   use ExUnit.Case
 
   test "can rename a NIF with an attribute" do
-    assert RustlerTest.nif_attrs_can_rename()
+    assert RustlerTest.nif_attrs_can_rename!()
   end
 end