diff --git a/Lib/test/test_long.py b/Lib/test/test_long.py
--- a/Lib/test/test_long.py
+++ b/Lib/test/test_long.py
@@ -1102,6 +1102,7 @@ class LongTest(unittest.TestCase):
         self.assertEqual((-1).to_bytes(5, 'big', signed=True),
                          b'\xff\xff\xff\xff\xff')
         self.assertRaises(OverflowError, (1).to_bytes, 0, 'big')
+        self.assertRaises(OverflowError, (-1).to_bytes, 0, 'big', signed=True)
 
     def test_from_bytes(self):
         def check(tests, byteorder, signed=False):
diff --git a/Objects/longobject.c b/Objects/longobject.c
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -890,6 +890,10 @@ _PyLong_AsByteArray(PyLongObject* v,
         pincr = -1;
     }
 
+    /* fast path for n.to_bytes(0, ...) - this also fixes #27623 */
+    if (ndigits && !n)
+        goto Overflow;
+
     /* Copy over all the Python digits.
        It's crucial that every Python digit except for the MSD contribute
        exactly PyLong_SHIFT bits to the total, so first assert that the int is