diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
index 47547396b8cb54b..e3b40a0882e0a13 100644
--- a/Lib/test/test_base64.py
+++ b/Lib/test/test_base64.py
@@ -511,6 +511,9 @@ def test_a85decode(self):
         eq(base64.a85decode(b'y+<U', foldspaces=True, adobe=False), b' '*6)
         eq(base64.a85decode(b'y+9', foldspaces=True, adobe=False), b' '*5)
 
+        self.assertRaises(ValueError, base64.a85decode, b'aaaay', foldspaces=True)
+        eq(base64.a85decode(b'aaaaay', foldspaces=True), b'\xc9\x80\x0b@    ')
+
         self.check_other_types(base64.a85decode, b'GB\\6`E-ZP=Df.1GEb>',
                                b"www.python.org")