diff --git a/src/cffi.h b/src/cffi.h
index c5e2c088..1ea7454e 100644
--- a/src/cffi.h
+++ b/src/cffi.h
@@ -484,77 +484,4 @@ inline void add_module_c(VM* vm){
     add_refl_type("void_p", sizeof(void*), {});
 }
 
-struct Int32Flags{
-    PY_CLASS(Int32Flags, builtins, int32flags)
-
-    uint32_t value;
-    Int32Flags(uint32_t value) : value(value) {}
-
-    operator int32_t() const { return value; }
-    operator uint32_t() const { return value; }
-
-    static void _register(VM* vm, PyObject* mod, PyObject* type){
-        vm->bind_constructor<-1>(type, [](VM* vm, ArgsView args){
-            vm->check_args_size(args.size(), 1+0, 1+1);
-            uint32_t value = CAST_DEFAULT(uint32_t, 1, 0);
-            return VAR_T(Int32Flags, value);
-        });
-
-        vm->bind__repr__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* self){
-            uint32_t value = _CAST(Int32Flags&, self).value;
-            std::string str;
-            for(int i=0; i<32; ++i) str += (value & (1<<i)) ? '1' : '0';
-            std::reverse(str.begin(), str.end());
-            return VAR(str);
-        });
-
-        vm->bind__and__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* lhs, PyObject* rhs){
-            uint32_t value = _CAST(Int32Flags&, lhs).value;
-            if(!is_non_tagged_type(rhs, Int32Flags::_type(vm))) return vm->NotImplemented;
-            return VAR_T(Int32Flags, value & _CAST(Int32Flags&, rhs).value);
-        });
-
-        vm->bind__or__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* lhs, PyObject* rhs){
-            uint32_t value = _CAST(Int32Flags&, lhs).value;
-            if(!is_non_tagged_type(rhs, Int32Flags::_type(vm))) return vm->NotImplemented;
-            return VAR_T(Int32Flags, value | _CAST(Int32Flags&, rhs).value);
-        });
-
-        vm->bind__xor__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* lhs, PyObject* rhs){
-            uint32_t value = _CAST(Int32Flags&, lhs).value;
-            if(!is_non_tagged_type(rhs, Int32Flags::_type(vm))) return vm->NotImplemented;
-            return VAR_T(Int32Flags, value ^ _CAST(Int32Flags&, rhs).value);
-        });
-
-        vm->bind__lshift__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* lhs, PyObject* rhs){
-            uint32_t value = _CAST(Int32Flags&, lhs).value;
-            if(!is_int(rhs)) return vm->NotImplemented;
-            return VAR_T(Int32Flags, value << _CAST(i64, rhs));
-        });
-
-        vm->bind__rshift__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* lhs, PyObject* rhs){
-            uint32_t value = _CAST(Int32Flags&, lhs).value;
-            if(!is_int(rhs)) return vm->NotImplemented;
-            return VAR_T(Int32Flags, value >> _CAST(i64, rhs));
-        });
-
-        vm->bind__getitem__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* self, PyObject* i){
-            uint32_t value = _CAST(Int32Flags&, self).value;
-            int index = CAST(i64, i);
-            index = vm->normalized_index(index, 32);
-            int ok = value & (1 << index);
-            return VAR(ok);
-        });
-
-        vm->bind__setitem__(PK_OBJ_GET(Type, type), [](VM* vm, PyObject* self, PyObject* i, PyObject* v){
-            uint32_t& value = _CAST(Int32Flags&, self).value;
-            int index = CAST(i64, i);
-            index = vm->normalized_index(index, 32);
-            bool ok = CAST(i64, v) != 0;
-            if(ok) value |= (1 << index);
-            else value &= ~(1 << index);
-        });
-    }
-};
-
 }   // namespace pkpy
\ No newline at end of file
diff --git a/src/obj.h b/src/obj.h
index a27c3a69..a548773e 100644
--- a/src/obj.h
+++ b/src/obj.h
@@ -306,7 +306,7 @@ __T _py_cast(VM* vm, PyObject* obj) {
 #define _CAST(T, x) _py_cast<T>(vm, x)
 
 #define CAST_F(x) vm->num_to_float(x)
-#define CAST_DEFAULT(T, i, default_value) (args[i] != vm->None) ? py_cast<T>(vm, args[i]) : (default_value)
+#define CAST_DEFAULT(T, x, default_value) (x != vm->None) ? py_cast<T>(vm, x) : (default_value)
 
 /*****************************************************************/
 template<>
diff --git a/src/pocketpy.h b/src/pocketpy.h
index ba164e2d..ee9e57c4 100644
--- a/src/pocketpy.h
+++ b/src/pocketpy.h
@@ -1180,7 +1180,6 @@ inline void init_builtins(VM* _vm) {
     ArrayIter::register_class(_vm, _vm->builtins);
     StringIter::register_class(_vm, _vm->builtins);
     Generator::register_class(_vm, _vm->builtins);
-    Int32Flags::register_class(_vm, _vm->builtins);
 }
 
 inline void add_module_timeit(VM* vm){