diff --git a/Crypto/Cipher/Types.hs b/Crypto/Cipher/Types.hs
--- a/Crypto/Cipher/Types.hs
+++ b/Crypto/Cipher/Types.hs
@@ -267,7 +267,7 @@
                                | otherwise  -> Right $ Key sm
             KeySizeEnum l | smLen `elem` l  -> Right $ Key sm
                           | otherwise       -> Left $ KeyErrorInvalid ("valid size: " ++ show l)
-            KeySizeFixed v | smLen < v      -> Right $ Key sm
+            KeySizeFixed v | smLen == v     -> Right $ Key sm
                            | otherwise      -> Left $ KeyErrorInvalid ("valid size: " ++ show v)
 
 cbcEncryptGeneric :: BlockCipher cipher => cipher -> IV cipher -> ByteString -> ByteString
diff --git a/crypto-cipher-types.cabal b/crypto-cipher-types.cabal
--- a/crypto-cipher-types.cabal
+++ b/crypto-cipher-types.cabal
@@ -1,5 +1,5 @@
 Name:                crypto-cipher-types
-Version:             0.0.3
+Version:             0.0.4
 Synopsis:            Generic cryptography cipher types
 Description:         Generic cryptography cipher types
 License:             BSD3