diff --git a/Data/ASN1/BitArray.hs b/Data/ASN1/BitArray.hs
--- a/Data/ASN1/BitArray.hs
+++ b/Data/ASN1/BitArray.hs
@@ -7,16 +7,16 @@
 --
 {-# LANGUAGE DeriveDataTypeable #-}
 module Data.ASN1.BitArray
-	( BitArray(..)
-	, BitArrayOutOfBound(..)
-	, bitArrayLength
-	, bitArrayGetBit
-	, bitArraySetBitValue
-	, bitArraySetBit
-	, bitArrayClearBit
-	, bitArrayGetData
-	, toBitArray
-	) where
+    ( BitArray(..)
+    , BitArrayOutOfBound(..)
+    , bitArrayLength
+    , bitArrayGetBit
+    , bitArraySetBitValue
+    , bitArraySetBit
+    , bitArrayClearBit
+    , bitArrayGetData
+    , toBitArray
+    ) where
 
 import Data.Bits
 import Data.Word
@@ -28,12 +28,14 @@
 
 -- | throwed in case of out of bounds in the bitarray.
 data BitArrayOutOfBound = BitArrayOutOfBound Word64
-	deriving (Show,Eq,Typeable)
+    deriving (Show,Eq,Typeable)
 instance Exception BitArrayOutOfBound
 
 -- | represent a bitarray / bitmap
+--
+-- the memory representation start at bit 0
 data BitArray = BitArray Word64 ByteString
-	deriving (Show,Eq)
+    deriving (Show,Eq)
 
 -- | returns the length of bits in this bitarray
 bitArrayLength :: BitArray -> Word64
@@ -45,22 +47,22 @@
 -- | get the nth bits
 bitArrayGetBit :: BitArray -> Word64 -> Bool
 bitArrayGetBit (BitArray l d) n
-	| n >= l    = bitArrayOutOfBound n
-	| otherwise = flip testBit (7-fromIntegral bitn) $ B.index d (fromIntegral offset)
-		where (offset, bitn) = n `divMod` 8
+    | n >= l    = bitArrayOutOfBound n
+    | otherwise = flip testBit (7-fromIntegral bitn) $ B.index d (fromIntegral offset)
+        where (offset, bitn) = n `divMod` 8
 
 -- | set the nth bit to the value specified
 bitArraySetBitValue :: BitArray -> Word64 -> Bool -> BitArray
 bitArraySetBitValue (BitArray l d) n v
-	| n >= l    = bitArrayOutOfBound n
-	| otherwise =
-		let (before,after) = B.splitAt (fromIntegral offset) d in
-		-- array bound check before prevent fromJust from failing.
-		let (w,remaining) = fromJust $ B.uncons after in
-		BitArray l (before `B.append` (setter w (fromIntegral bitn) `B.cons` remaining))
-		where
-			(offset, bitn) = n `divMod` 8
-			setter = if v then setBit else clearBit
+    | n >= l    = bitArrayOutOfBound n
+    | otherwise =
+        let (before,after) = B.splitAt (fromIntegral offset) d in
+        -- array bound check before prevent fromJust from failing.
+        let (w,remaining) = fromJust $ B.uncons after in
+        BitArray l (before `B.append` (setter w (7-fromIntegral bitn) `B.cons` remaining))
+  where
+        (offset, bitn) = n `divMod` 8
+        setter = if v then setBit else clearBit
 
 -- | set the nth bits
 bitArraySetBit :: BitArray -> Word64 -> BitArray
@@ -77,4 +79,4 @@
 -- | number of bit to skip at the end (padding)
 toBitArray :: ByteString -> Int -> BitArray
 toBitArray l toSkip =
-	BitArray (fromIntegral (B.length l * 8 - fromIntegral toSkip)) l
+    BitArray (fromIntegral (B.length l * 8 - fromIntegral toSkip)) l
diff --git a/asn1-types.cabal b/asn1-types.cabal
--- a/asn1-types.cabal
+++ b/asn1-types.cabal
@@ -1,5 +1,5 @@
 Name:                asn1-types
-Version:             0.2.2
+Version:             0.2.3
 Description:         ASN.1 standard types
 License:             BSD3
 License-file:        LICENSE