diff --git a/py/objint.c b/py/objint.c
index 222aa1d..2a7e3f3 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -291,7 +291,7 @@
 }
 
 // This is called only with strings whose value doesn't fit in SMALL_INT
-mp_obj_t mp_obj_new_int_from_str_len(const char **str, mp_uint_t len, bool neg, mp_uint_t base) {
+mp_obj_t mp_obj_new_int_from_str_len(const char **str, size_t len, bool neg, unsigned int base) {
     mp_raise_msg(&mp_type_OverflowError, "long int not supported in this build");
     return mp_const_none;
 }