diff --git a/py/objint.c b/py/objint.c
index 2eabff8..2c71f51 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -193,7 +193,7 @@
 
 // This is called for operations on SMALL_INT that are not handled by mp_unary_op
 mp_obj_t mp_obj_int_unary_op(int op, mp_obj_t o_in) {
-    return MP_OBJ_NULL;
+    return MP_OBJ_NOT_SUPPORTED;
 }
 
 // This is called for operations on SMALL_INT that are not handled by mp_binary_op
@@ -262,7 +262,7 @@
             return mp_binary_op(op, rhs_in, lhs_in);
         }
     }
-    return MP_OBJ_NULL;
+    return MP_OBJ_NOT_SUPPORTED;
 }
 
 // this is a classmethod