diff --git a/crypto-cipher-tests.cabal b/crypto-cipher-tests.cabal
--- a/crypto-cipher-tests.cabal
+++ b/crypto-cipher-tests.cabal
@@ -1,5 +1,5 @@
 Name:                crypto-cipher-tests
-Version:             0.0.3
+Version:             0.0.4
 Synopsis:            Generic cryptography cipher tests
 Description:         Generic cryptography cipher tests
 License:             BSD3
diff --git a/tests/Tests.hs b/tests/Tests.hs
--- a/tests/Tests.hs
+++ b/tests/Tests.hs
@@ -13,7 +13,7 @@
 instance Cipher XorCipher where
     cipherInit _    = XorCipher
     cipherName _    = "xor"
-    cipherKeySize _ = Just 0
+    cipherKeySize _ = KeySizeRange 1 32
 
 instance BlockCipher XorCipher where
     blockSize  _   = 16