diff --git a/Crypto/Cipher/AES.hs b/Crypto/Cipher/AES.hs
index 61b81cf..97a1801 100644
--- a/Crypto/Cipher/AES.hs
+++ b/Crypto/Cipher/AES.hs
@@ -48,6 +48,7 @@ instance Cipher AES256 where
     cipherKeySize _ = KeySizeFixed 32
     cipherInit k    = AES256 <$> (initAES =<< validateKeySize (undefined :: AES256) k)
 
+
 #define INSTANCE_BLOCKCIPHER(CSTR) \
 instance BlockCipher CSTR where \
     { blockSize _ = 16 \
diff --git a/Crypto/Cipher/AES/Primitive.hs b/Crypto/Cipher/AES/Primitive.hs
index 5169366..26aeb61 100644
--- a/Crypto/Cipher/AES/Primitive.hs
+++ b/Crypto/Cipher/AES/Primitive.hs
@@ -101,7 +101,7 @@ ocbMode aes = AEADModeImpl
     , aeadImplFinalize     = ocbFinish aes
     }
 
--- | Create an AES AEAD implementation for GCM
+-- | Create an AES AEAD implementation for CCM
 ccmMode :: AES -> AEADModeImpl AESCCM
 ccmMode aes = AEADModeImpl
     { aeadImplAppendHeader = ccmAppendAAD aes
@@ -110,6 +110,7 @@ ccmMode aes = AEADModeImpl
     , aeadImplFinalize     = ccmFinish aes
     }
 
+
 -- | AES Context (pre-processed key)
 newtype AES = AES ScrubbedBytes
     deriving (NFData)
diff --git a/cbits/cryptonite_aes.c b/cbits/cryptonite_aes.c
index 7e0b723..6fdc1e0 100644
--- a/cbits/cryptonite_aes.c
+++ b/cbits/cryptonite_aes.c
@@ -437,18 +437,18 @@ void cryptonite_aes_gcm_finish(uint8_t *tag, aes_gcm *gcm, aes_key *key)
 	}
 }
 
-static inline int ccm_b0_flags(int has_adata, int m, int l)
+static inline uint8_t ccm_b0_flags(uint32_t has_adata, uint32_t m, uint32_t l)
 {
 	return 8*m + l + (has_adata? 64: 0);
 }
 
 /* depends on input size */
-static void ccm_encode_b0(block128* output, aes_ccm* ccm, int has_adata)
+static void ccm_encode_b0(block128* output, aes_ccm* ccm, uint32_t has_adata)
 {
 	int last = 15;
-	int m = ccm->length_M;
-	int l = ccm->length_L;
-	unsigned msg_len = ccm->length_input;
+	uint32_t m = ccm->length_M;
+	uint32_t l = ccm->length_L;
+	uint32_t msg_len = ccm->length_input;
 
 	block128_zero(output);
 	block128_copy(output, &ccm->nonce);
@@ -530,7 +530,7 @@ void cryptonite_aes_ccm_aad(aes_ccm *ccm, aes_key *key, uint8_t *input, uint32_t
 	block128 tmp;
 
 	if (ccm->length_aad != 0) return;
-	
+
 	ccm->length_aad = length;
 	int len_len;
 
@@ -940,7 +940,7 @@ void cryptonite_aes_generic_ccm_decrypt(uint8_t *output, aes_ccm *ccm, aes_key *
 	if (length != ccm->length_input) {
 		return;
 	}
-	
+
 	/* when aad is absent, reset b0 block */
 	if (ccm->length_aad == 0) {
 		ccm_encode_b0(&ccm->b0, ccm, 0); /* assume aad is present */
diff --git a/cbits/cryptonite_aes.h b/cbits/cryptonite_aes.h
index 9ac20b3..05e147d 100644
--- a/cbits/cryptonite_aes.h
+++ b/cbits/cryptonite_aes.h
@@ -55,7 +55,7 @@ typedef struct {
 	uint64_t length_input;
 } aes_gcm;
 
-/* size = 80 */
+/* size = 4*16+4*4= 80 */
 typedef struct {
 	aes_block xi;
 	aes_block header_cbcmac;
@@ -63,8 +63,8 @@ typedef struct {
 	aes_block nonce;
 	uint32_t length_aad;
 	uint32_t length_input;
-        uint32_t length_M;
-        uint32_t length_L;
+	uint32_t length_M;
+	uint32_t length_L;
 } aes_ccm;
 
 typedef struct {
diff --git a/tests/BlockCipher.hs b/tests/BlockCipher.hs
index 6e8f8af..2fc1248 100644
--- a/tests/BlockCipher.hs
+++ b/tests/BlockCipher.hs
@@ -220,7 +220,7 @@ testKATs kats cipher = testGroup "KAT"
         aeadInitNoErr mode ct iv =
             case aeadInit mode ct iv of
                 CryptoPassed a -> a
-                CryptoFailed _ -> error $ "cipher does'nt support aead mode: " ++ show mode
+                CryptoFailed _ -> error $ "cipher doesn't support aead mode: " ++ show mode
 ------------------------------------------------------------------------
 -- Properties
 ------------------------------------------------------------------------
diff --git a/tests/KAT_AES.hs b/tests/KAT_AES.hs
index a6c8182..cf098a3 100644
--- a/tests/KAT_AES.hs
+++ b/tests/KAT_AES.hs
@@ -7,6 +7,7 @@ import Data.Maybe
 import Crypto.Cipher.Types
 import qualified Crypto.Cipher.AES as AES
 import qualified Data.ByteString as B
+
 import qualified KAT_AES.KATECB as KATECB
 import qualified KAT_AES.KATCBC as KATCBC
 import qualified KAT_AES.KATXTS as KATXTS
@@ -49,8 +50,10 @@ toKatCCM (k,iv,h,i,o,m) =
            , aeadTaglen = m
            , aeadTag = at
            }
-  where ccmMVal x = fromMaybe CCM_M16 (lookup x [ (4, CCM_M4), (6, CCM_M6), (8, CCM_M8), (10, CCM_M10),
-                                                  (12, CCM_M12), (14, CCM_M14), (16, CCM_M16) ])
+  where ccmMVal x = fromMaybe (error $ "unsupported CCM tag length: " ++ show x) $
+                        lookup x [ (4, CCM_M4), (6, CCM_M6), (8, CCM_M8), (10, CCM_M10)
+                                 , (12, CCM_M12), (14, CCM_M14), (16, CCM_M16)
+                                 ]
         ctWithTag = B.drop (B.length h) o
         (ct, at)  = B.splitAt (B.length ctWithTag - m) ctWithTag
 
diff --git a/tests/KAT_AES/KATCCM.hs b/tests/KAT_AES/KATCCM.hs
index e9b2a1a..4f3c197 100644
--- a/tests/KAT_AES/KATCCM.hs
+++ b/tests/KAT_AES/KATCCM.hs
@@ -7,8 +7,8 @@ import qualified Data.ByteString as B
 type KATCCM = (B.ByteString, B.ByteString, B.ByteString, B.ByteString, B.ByteString, Int)
 
 vectors_aes128_enc :: [KATCCM]
-vectors_aes128_enc = [
-    ( {- key = -} "\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf"
+vectors_aes128_enc =
+  [ ( {- key = -} "\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf"
     , {- iv  = -} "\x00\x00\x00\x03\x02\x01\x00\xa0\xa1\xa2\xa3\xa4\xa5"
     , {- hdr = -} "\x00\x01\x02\x03\x04\x05\x06\x07"
     , {- in  = -} "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e"
@@ -151,4 +151,5 @@ vectors_aes128_enc = [
     , {- hdr = -} "\x6e\x37\xa6\xef\x54\x6d\x95\x5d\x34\xab\x60\x59"
     , {- in  = -} "\xab\xf2\x1c\x0b\x02\xfe\xb8\x8f\x85\x6d\xf4\xa3\x73\x81\xbc\xe3\xcc\x12\x85\x17\xd4"
     , {- out = -} "\x6e\x37\xa6\xef\x54\x6d\x95\x5d\x34\xab\x60\x59\xf3\x29\x05\xb8\x8a\x64\x1b\x04\xb9\xc9\xff\xb5\x8c\xc3\x90\x90\x0f\x3d\xa1\x2a\xb1\x6d\xce\x9e\x82\xef\xa1\x6d\xa6\x20\x59"
-    , {-  M  = -} 10) ]
+    , {-  M  = -} 10)
+  ]