--- a/Python/importdl.c	(index)
+++ b/Python/importdl.c	(working tree)
@@ -191,6 +191,11 @@ _Py_ext_module_loader_info_init_for_builtin(
         .hook_prefix=ascii_only_prefix,
         .newcontext=NULL,
     };
+    info->newcontext = PyUnicode_AsUTF8(name);
+    if (info->newcontext == NULL) {
+        _Py_ext_module_loader_info_clear(info);
+        return -1;
+    }
     return 0;
 }