diff --git a/python/jittor/test/test_nano_vector.py b/python/jittor/test/test_nano_vector.py
index 7697305a..0451dce2 100644
--- a/python/jittor/test/test_nano_vector.py
+++ b/python/jittor/test/test_nano_vector.py
@@ -38,6 +38,11 @@ class TestNanoVector(unittest.TestCase):
         a += [3,4]
         assert a == [1,2,3,4], a
 
+    def test_slice_bug(self):
+        a = jt.NanoVector([2,3,4,5])
+        assert a[:] == [2,3,4,5]
+        assert a[1:] == [3,4,5]
+
 
 if __name__ == "__main__":
     unittest.main()
\ No newline at end of file
diff --git a/src/misc/nano_vector.h b/src/misc/nano_vector.h
index 59dfb6d9..32b99cc0 100644
--- a/src/misc/nano_vector.h
+++ b/src/misc/nano_vector.h
@@ -21,7 +21,7 @@ static inline int lzcnt(int64 v) {
 }
 
 struct Slice {
-    int start, stop, step;
+    int64 start, stop, step, mask;
 };
 
 // @pyjt(NanoVector)
@@ -108,9 +108,10 @@ struct NanoVector {
 
     // @pyjt(__map_getitem__)
     inline NanoVector slice(Slice slice) {
+        if (slice.mask&2) slice.stop = size();
         if (slice.start<0) slice.start += size();
         if (slice.stop<0) slice.stop += size();
-        ASSERT(slice.start>=0 && slice.stop>=0 && slice.start<size() && slice.stop<size())
+        ASSERT(slice.start>=0 && slice.stop>=0 && slice.start<size() && slice.stop<=size())
             << "slice overflow:" << slice.start << slice.stop << slice.step;
         NanoVector v;
         if (slice.step>0) {
diff --git a/src/pyjt/py_converter.h b/src/pyjt/py_converter.h
index dde2897e..1e497359 100644
--- a/src/pyjt/py_converter.h
+++ b/src/pyjt/py_converter.h
@@ -123,8 +123,13 @@ DEF_IS(Slice, bool) is_type(PyObject* obj) {
 }
 DEF_IS(Slice, T) from_py_object(PyObject* obj) {
     Py_ssize_t start, stop, step;
+    auto slice = (PySliceObject*)obj;
+
     PySlice_Unpack(obj, &start, &stop, &step);
-    return {(int)start, (int)stop, (int)step};
+    return {start, stop, step, 
+        (slice->start == Py_None) |
+        ((slice->stop == Py_None) << 1) |
+        ((slice->step == Py_None) << 2)};
 }
 
 #define GET_RAW_PTR(T, obj) ((T*)(((char*)obj) + sizeof(PyObject)))