diff --git a/CONTRIBUTORS b/CONTRIBUTORS
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -1,3 +1,4 @@
 - <harmen@millionmonkeys.nl>
 - Marc Weber <marco-oweber@gmx.de>
 - Anton van Straaten <anton@appsolutions.com>
+- Kirk Peterson <necrobious@gmail.com>
diff --git a/FEATURES b/FEATURES
--- a/FEATURES
+++ b/FEATURES
@@ -19,7 +19,7 @@
   * Expiring either on a given date, or number of seconds from current time
  * Setting the storage class (Reduced Redundancy or Standard) for new objects
  * Rewrite storage class of existing objects
-
+ * MD5 message integrity check for sent objects (optional)
 
 Missing feature list (incomplete).  We know the following features are not
 yet supported.  Some features may be available without changing the
diff --git a/Network/AWS/Authentication.hs b/Network/AWS/Authentication.hs
--- a/Network/AWS/Authentication.hs
+++ b/Network/AWS/Authentication.hs
@@ -97,6 +97,7 @@
 headersFromAction = map (\(k,v) -> case k of
                                     "Content-Type" -> Header HdrContentType v
                                     "Content-Length" -> Header HdrContentLength v
+                                    "Content-MD5" -> Header HdrContentMD5 v
                                     otherwise -> Header (HdrCustom k) (mimeEncodeQP v))
                     . s3metadata
 
diff --git a/Network/AWS/S3Object.hs b/Network/AWS/S3Object.hs
--- a/Network/AWS/S3Object.hs
+++ b/Network/AWS/S3Object.hs
@@ -11,7 +11,7 @@
 
 module Network.AWS.S3Object (
   -- * Function Types
-  sendObject, copyObject, copyObjectWithReplace, getObject,
+  sendObject, sendObjectMIC, copyObject, copyObjectWithReplace, getObject,
   getObjectInfo, deleteObject, publicUriForSeconds,
   publicUriUntilTime, setStorageClass, getStorageClass,
   rewriteStorageClass,
@@ -27,8 +27,11 @@
 import System.Time
 import Data.List.Utils
 import Data.List(lookup)
+import Data.Digest.MD5(hash)
+import Codec.Binary.Base64 (encode)
 
 import qualified Data.ByteString.Lazy.Char8 as L
+import qualified Data.ByteString.Lazy as LO
 
 -- | An object that can be stored and retrieved from S3.
 data S3Object =
@@ -109,6 +112,18 @@
                                obj_headers obj)
                               (obj_data obj) PUT)
        return (either Left (\_ -> Right ()) res)
+
+-- | Send data for an object, with message integrity check.  This
+--   version of sendObject will add an MD5 message integrity check so
+--   that transmission errors will be detected, but requires the message
+--   be read into memory before being sent.
+sendObjectMIC :: AWSConnection      -- ^ AWS connection information
+              -> S3Object           -- ^ Object to add to a bucket
+              -> IO (AWSResult ())  -- ^ Server response
+sendObjectMIC aws obj = sendObject aws obj_w_header where
+    obj_w_header = obj { obj_headers = (obj_headers obj) ++ md5_header }
+    md5_header = [("Content-MD5", (mkMD5 (obj_data obj)))]
+    mkMD5 = encode . hash . LO.unpack
 
 -- | Create a pre-signed request URI.  Anyone can use this to request
 --   an object until the specified date.
diff --git a/Tests.hs b/Tests.hs
--- a/Tests.hs
+++ b/Tests.hs
@@ -31,6 +31,7 @@
     TestList
     [
      TestLabel "S3 Operations Test" s3OperationsTest,
+     TestLabel "S3 Message Integrity Check" s3MessageIntegrityCheckTest,
      TestLabel "S3 Copy Test" s3CopyTest,
      TestLabel "S3 Copy/Replace Test" s3CopyReplaceTest,
      TestLabel "S3 Location Test" s3LocationTest,
@@ -82,6 +83,18 @@
                  testBucketGone c bucket
              )
 
+s3MessageIntegrityCheckTest =
+    TestCase (
+              do c <- getConn
+                 bucket <- testCreateBucket c
+                 testGetBucketLocation c bucket "US"
+                 let testObj = testObjectTemplate {obj_bucket = bucket}
+                 -- Object send
+                 testSendObjectMIC c testObj
+                 -- Object get
+                 testGetObject c testObj
+             )
+
 s3LocationTest =
     TestCase (
               do c <- getConn
@@ -234,6 +247,12 @@
 testSendObject :: AWSConnection -> S3Object -> IO ()
 testSendObject c o =
     do r <- sendObject c o
+       failOnError r ()
+              (const $ assertBool "object send" True)
+
+testSendObjectMIC :: AWSConnection -> S3Object -> IO ()
+testSendObjectMIC c o =
+    do r <- sendObjectMIC c o
        failOnError r ()
               (const $ assertBool "object send" True)
 
diff --git a/hS3.cabal b/hS3.cabal
--- a/hS3.cabal
+++ b/hS3.cabal
@@ -1,5 +1,5 @@
 Name:           hS3
-Version:        0.5.7
+Version:        0.5.8
 License:        BSD3
 License-file:   LICENSE
 Cabal-Version: >= 1.6
@@ -28,8 +28,8 @@
                     examples/uploadFile.hs
 
 source-repository head
-  type:     darcs
-  location: http://gregheartsfield.com/repos/hS3/
+  type:     git
+  location: http://github.com/errge/hS3
 
 Library