diff --git a/py/objexcept.c b/py/objexcept.c
index b87609a6b..380bc3534 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -118,7 +118,7 @@ STATIC void mp_obj_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_pr
             if (o->base.type == &mp_type_OSError && MP_OBJ_IS_SMALL_INT(o->args->items[0])) {
                 qstr qst = mp_errno_to_str(o->args->items[0]);
                 if (qst != MP_QSTR_NULL) {
-                    mp_printf(print, "[Errno %d] %q", MP_OBJ_SMALL_INT_VALUE(o->args->items[0]), qst);
+                    mp_printf(print, "[Errno " INT_FMT "] %q", MP_OBJ_SMALL_INT_VALUE(o->args->items[0]), qst);
                     return;
                 }
             }