1 files changed, 2 insertions, 2 deletions
diff --git a/python/genkat_aead.py b/python/genkat_aead.py
index 6d7ca51..5bce05f 100755
--- a/python/genkat_aead.py
+++ b/python/genkat_aead.py
@@ -28,8 +28,8 @@ class DecryptionError(Exception):
     def __str__(self):
         return '({s.mode} / {s.keylen}) Expected {exp}; got {act}'.format(
             s=self,
-            exp=bstr(self.expected),
-            act=bstr(self.actual)
+            exp=bstr(self.expected) if self.expected is not None else 'NONE',
+            act=bstr(self.actual) if self.actual is not None else 'NONE'
         )