1 files changed, 1 insertions, 1 deletions
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 05bdbfecac..859cb11116 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -370,7 +370,7 @@ STATIC mp_obj_t mp_builtin_ord(mp_obj_t o_in) {
             "ord expects a character"));
     } else {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
-            "ord() expected a character, but string of length %d found", len));
+            "ord() expected a character, but string of length %d found", (int)len));
     }
 }
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_ord_obj, mp_builtin_ord);