diff --git a/py/objbool.c b/py/objbool.c
index cfab7db..da9a678 100644
--- a/py/objbool.c
+++ b/py/objbool.c
@@ -27,7 +27,7 @@
     switch (n_args) {
         case 0: return mp_const_false;
         case 1: if (rt_is_true(args[0])) { return mp_const_true; } else { return mp_const_false; }
-        default: nlr_jump(mp_obj_new_exception_msg_1_arg(MP_QSTR_TypeError, "bool takes at most 1 argument, %d given", (void*)(machine_int_t)n_args));
+        default: nlr_jump(mp_obj_new_exception_msg_varg(MP_QSTR_TypeError, "bool takes at most 1 argument, %d given", n_args));
     }
 }