diff --git a/py/obj.c b/py/obj.c
index dc69194672..64c52eeb76 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -326,7 +326,12 @@ bool mp_obj_get_int_maybe(mp_const_obj_t arg, mp_int_t *value) {
     } else if (mp_obj_is_exact_type(arg, &mp_type_int)) {
         *value = mp_obj_int_get_checked(arg);
     } else {
-        return false;
+        arg = mp_unary_op(MP_UNARY_OP_INT_MAYBE, (mp_obj_t)arg);
+        if (arg != MP_OBJ_NULL) {
+            *value = mp_obj_int_get_checked(arg);
+        } else {
+            return false;
+        }
     }
     return true;
 }
diff --git a/tests/basics/string_format_modulo.py b/tests/basics/string_format_modulo.py
index 01f8e7ed24..14b4a6a484 100644
--- a/tests/basics/string_format_modulo.py
+++ b/tests/basics/string_format_modulo.py
@@ -13,6 +13,12 @@ print("=%s=" % [1, 2])
 print("=%s=" % "str")
 print("=%r=" % "str")
 
+# test calling __int__
+class A:
+    def __int__(self):
+        return 123
+print("%d" % A())
+
 try:
     print("=%s=%s=" % 1)
 except TypeError: