diff --git a/mangopay.cabal b/mangopay.cabal
--- a/mangopay.cabal
+++ b/mangopay.cabal
@@ -1,5 +1,5 @@
 name:           mangopay
-version:        1.3
+version:        1.4
 cabal-version:  >= 1.8
 build-type:     Simple
 author:         JP Moresmau <jpmoresmau@gmail.com>
@@ -123,7 +123,8 @@
                   Web.MangoPay.CardsTest,
                   Web.MangoPay.RefundsTest,
                   Web.MangoPay.AccountsTest,
-                  Web.MangoPay.PayoutsTest
+                  Web.MangoPay.PayoutsTest,
+                  Web.MangoPay.SimpleTest
   hs-source-dirs:
                   test,
                   src
diff --git a/src/Web/MangoPay.hs b/src/Web/MangoPay.hs
--- a/src/Web/MangoPay.hs
+++ b/src/Web/MangoPay.hs
@@ -16,6 +16,9 @@
         ,PagedList(..)
         ,MPUsableMonad
         ,ToHtQuery(..)
+        ,CardExpiration(..)
+        ,readCardExpiration
+        ,writeCardExpiration
         
         -- access
         ,createCredentialsSecret
diff --git a/src/Web/MangoPay/Cards.hs b/src/Web/MangoPay/Cards.hs
--- a/src/Web/MangoPay/Cards.hs
+++ b/src/Web/MangoPay/Cards.hs
@@ -35,7 +35,7 @@
 -- | credit card information
 data CardInfo = CardInfo {
   ciNumber :: Text
-  ,ciExpire :: Text
+  ,ciExpire :: CardExpiration
   ,ciCSC :: Text
   } deriving (Show,Read,Eq,Ord,Typeable)
 
@@ -123,7 +123,7 @@
   cId :: CardID
   ,cCreationDate :: POSIXTime 
   ,cTag :: Maybe Text  
-  ,cExpirationDate   :: Text -- ^  MMYY
+  ,cExpirationDate   :: CardExpiration -- ^  MMYY
   ,cAlias :: Text -- ^ Example: 497010XXXXXX4414
   ,cCardProvider  :: Text -- ^ The card provider, it could be « CB », « VISA », « MASTERCARD », etc.
   ,cCardType :: Text -- ^ « CB_VISA_MASTERCARD » is the only value available yet
diff --git a/src/Web/MangoPay/Monad.hs b/src/Web/MangoPay/Monad.hs
--- a/src/Web/MangoPay/Monad.hs
+++ b/src/Web/MangoPay/Monad.hs
@@ -213,7 +213,7 @@
   let cr=CallRecord req' mpres
   -- log call
   $(logCall) cr
-  return $ recordResult cr
+  recordResult cr
 
 -- | get a JSON response from a request to MangoPay
 -- MangoPay returns either a result, or an error
diff --git a/src/Web/MangoPay/Types.hs b/src/Web/MangoPay/Types.hs
--- a/src/Web/MangoPay/Types.hs
+++ b/src/Web/MangoPay/Types.hs
@@ -1,11 +1,13 @@
-{-# LANGUAGE DeriveDataTypeable, OverloadedStrings, ScopedTypeVariables, TypeSynonymInstances, FlexibleInstances, TemplateHaskell #-}
+{-# LANGUAGE DeriveDataTypeable, OverloadedStrings, ScopedTypeVariables, TypeSynonymInstances, FlexibleContexts, FlexibleInstances, TemplateHaskell, PatternGuards #-}
 -- | useful types and simple accessor functions
 module Web.MangoPay.Types where
 
 
 import Control.Applicative
-import Control.Exception.Base (Exception,throw)
+import Control.Exception.Lifted (Exception, throwIO)
+import Control.Monad.Base (MonadBase)
 import Data.Text as T hiding (singleton)
+import Data.Text.Read as T
 import Data.Typeable (Typeable)
 import Data.ByteString  as BS (ByteString)
 import Data.Time.Clock.POSIX (POSIXTime)
@@ -20,12 +22,14 @@
 import Control.Monad.Logger
 import Data.Aeson.Encode (encodeToTextBuilder)
 import Data.Text.Lazy.Builder (fromText, toLazyText, singleton)
-import Data.Monoid ((<>))
+import Data.Monoid ((<>), mempty)
 import Data.Text.Lazy (toStrict)
-import Data.String (fromString)
+import Data.String (fromString, IsString)
 import qualified Data.Vector as V (length)
 import Language.Haskell.TH
 import Language.Haskell.TH.Syntax (qLocation)
+import Text.Printf (printf)
+import qualified Data.ByteString.Lazy as BS (toStrict)
 
 -- | the MangoPay access point
 data AccessPoint = Sandbox | Production | Custom ByteString
@@ -160,6 +164,46 @@
 -- | alias for Currency
 type Currency=Text
 
+-- | the expiration date of a card
+data CardExpiration = CardExpiration {
+  ceMonth :: Int
+  ,ceYear :: Int
+  }
+  deriving (Show,Read,Eq,Ord,Typeable)
+
+-- | read Card Expiration from text representation (MMYY)
+readCardExpiration :: T.Reader CardExpiration
+readCardExpiration t |
+  4 == T.length t,
+  (m,y)<-T.splitAt 2 t=do
+    im<-T.decimal m
+    iy<-T.decimal y
+    return (CardExpiration (fst im) (fst iy), "")
+readCardExpiration _ =Left "Incorrect length"
+
+-- | write card expiration
+writeCardExpiration :: CardExpiration -> Text
+writeCardExpiration (CardExpiration m y)=let
+  -- yes I know about text-format, but I don't think performance is that critical here to warrant another dependency
+  sm=printf "%02d" $ checkRng m
+  sy=printf "%02d" $ checkRng y
+  in T.concat [pack sm, pack sy]
+  where
+    -- | check range fits in two digits
+    checkRng :: Int -> Int
+    checkRng i=if i > 99 then i `mod` 100 else i
+
+-- | read Card Expiration from JSON string (MMYY)
+instance FromJSON CardExpiration where
+  parseJSON (String s) |
+    Right (ce,"")<- readCardExpiration s=pure ce
+  parseJSON _=fail "CardExpiration"
+
+instance IsString CardExpiration where
+  fromString s
+    | Right (ce,"")<-readCardExpiration $ fromString s=ce
+  fromString _=error "CardExpiration"
+
 -- | a structure holding the information of an API call
 data CallRecord a = CallRecord {
     crReq :: H.Request -- ^ the request to MangoPay
@@ -181,6 +225,12 @@
   pathB=fromText $ TE.decodeUtf8 $ H.path req
   -- log the query string if any
   qsB=fromText $ TE.decodeUtf8 $ H.queryString req
+  postB=if H.method req==HT.methodPost 
+    then case H.requestBody req of
+      (H.RequestBodyBS b)->fromText (TE.decodeUtf8 b) <> " -> "
+      (H.RequestBodyLBS b)->fromText $ TE.decodeUtf8 $ BS.toStrict b <> " -> "
+      _->mempty
+    else mempty
   resB=case res of
     -- log error
     Left e->fromString $ show e
@@ -189,14 +239,14 @@
       Array arr->fromString (show $ V.length arr) <> " values"
       -- we have a simple value we can log it
       _->encodeToTextBuilder v
-  in toStrict . toLazyText $ methB <> singleton ' ' <> pathB <> qsB <> ": " <> resB
+  in toStrict . toLazyText $ methB <> singleton ' ' <> pathB <> qsB <> ": " <> postB <> resB
 
 -- | the result
 -- if we have a proper result we return it
 -- if we have an error we throw it
-recordResult :: CallRecord a-> a
-recordResult (CallRecord _ (Left err))=throw err
-recordResult (CallRecord _ (Right (_,a)))=a
+recordResult :: MonadBase IO m => CallRecord a -> m a
+recordResult (CallRecord _ (Left err))=throwIO err
+recordResult (CallRecord _ (Right (_,a)))=return a
 
 -- | log a CallRecord
 -- MonadLogger doesn't expose a function with a dynamic log level...
diff --git a/test/Web/MangoPay/CardsTest.hs b/test/Web/MangoPay/CardsTest.hs
--- a/test/Web/MangoPay/CardsTest.hs
+++ b/test/Web/MangoPay/CardsTest.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings, ScopedTypeVariables #-}
 {-# OPTIONS_GHC -F -pgmF htfpp #-}
 -- | test cards
 module Web.MangoPay.CardsTest where
@@ -11,14 +11,23 @@
 import Test.HUnit (Assertion)
 
 import qualified Data.Text as T
+import qualified Control.Exception.Lifted as L
 
--- | test a card registration
-test_Card :: Assertion
-test_Card = do
+-- | test a card registration using euro currency
+test_CardEUR :: Assertion
+test_CardEUR = doTestCard "EUR"
+
+-- | test a card registration using dollar currency
+test_CardUSD :: Assertion
+test_CardUSD = doTestCard "USD"
+
+-- | perform the actual test of card registration in the provided currency
+doTestCard :: T.Text->Assertion
+doTestCard curr=L.handle (\(e::MpException)->assertFailure (show e)) $ do
   usL<-testMP $ listUsers (Just $ Pagination 1 1)
   assertEqual 1 (length $ plData usL)
   let uid=urId $ head $ plData usL
-  let cr1=mkCardRegistration uid "EUR"
+  let cr1=mkCardRegistration uid curr
   cr2<-testMP $ storeCardRegistration cr1
   assertBool (isJust $ crId cr2)
   assertBool (isJust $ crCreationDate cr2)
@@ -36,14 +45,15 @@
   assertEqual cid $ cId c
   assertBool $ not $ T.null $ cAlias c 
   assertBool $ not $ T.null $ cCardProvider c
-  assertBool $ not $ T.null $ cExpirationDate c
+  assertEqual (ciExpire testCardInfo1) (cExpirationDate c)
+  --assertBool $ not $ T.null $ cExpirationDate c
   assertEqual UNKNOWN $ cValidity c
   assertBool $ cActive c
   assertEqual uid $ cUserId c
   assertEqual "CB_VISA_MASTERCARD" $ cCardType c
   cs<-testMP $ getAll $ listCards uid
   assertBool $ not $ null cs
-  assertBool $ any (\ c1 -> cId c == cid) cs
+  assertBool $ any (\ c1 -> cId c1 == cid) cs
   
  
   
diff --git a/test/Web/MangoPay/SimpleTest.hs b/test/Web/MangoPay/SimpleTest.hs
new file mode 100644
--- /dev/null
+++ b/test/Web/MangoPay/SimpleTest.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# OPTIONS_GHC -F -pgmF htfpp #-}
+module Web.MangoPay.SimpleTest where
+
+import Web.MangoPay
+
+import qualified Data.Text as T
+import Test.Framework
+import Test.HUnit (Assertion)
+import Data.Either (rights)
+
+-- | test serialization of card expiration
+test_CardExpiration :: Assertion
+test_CardExpiration = do
+  let ece1=readCardExpiration "0225"
+  assertBool $ not $ null $ rights [ece1]
+  let Right (ce1,t1)=ece1
+  assertBool $ T.null t1
+  assertEqual (CardExpiration 2 25) ce1
+  assertEqual "0225" $ writeCardExpiration ce1
+  let ece2=readCardExpiration "1503"
+  assertBool $ not $ null $ rights [ece2]
+  let Right (ce2,t2)=ece2
+  assertBool $ T.null t2
+  assertEqual (CardExpiration 15 3) ce2
+  assertEqual "1503" $ writeCardExpiration ce2
+  let ce3 = CardExpiration 10 2034
+  assertEqual "1034" $ writeCardExpiration ce3
+  
diff --git a/test/Web/MangoPay/TestUtils.hs b/test/Web/MangoPay/TestUtils.hs
--- a/test/Web/MangoPay/TestUtils.hs
+++ b/test/Web/MangoPay/TestUtils.hs
@@ -130,7 +130,7 @@
     res<-liftM tsReceivedEvents $ readIORef testState
     a<-ops
     mapM_ (testSearchEvent a) evtTs
-    er<-waitForEvent res (map (testEvent a) evtTs) 5
+    er<-waitForEvent res (map (testEvent a) evtTs) 30
     assertEqual EventsOK er
     return a
 
@@ -235,7 +235,7 @@
                         liftIO $ case mevt of
                             Just evt->do
                                 pushReceivedEvent revts $ Right evt
-                                print evt
+                                putStrLn $ "Received event:" ++ show evt
                             Nothing->pushReceivedEvent revts $ Left $ UnhandledNotification $ show $ W.queryString req
                 return $ W.responseBuilder status200 [("Content-Type", "text/plain")] $ copyByteString "noop"
 
@@ -268,7 +268,7 @@
             "accessKeyRef" ?+ ak
             ,"data" ?+ pre
             ,"cardNumber" ?+ ciNumber ci
-            ,"cardExpirationDate" ?+ ciExpire ci
+            ,"cardExpirationDate" ?+ (writeCardExpiration $ ciExpire ci)
             ,"cardCvx" ?+ ciCSC ci]
     let req'=req {H.method=HT.methodPost
          , H.requestHeaders=[("content-type","application/x-www-form-urlencoded")]
diff --git a/test/mangopay-tests.hs b/test/mangopay-tests.hs
--- a/test/mangopay-tests.hs
+++ b/test/mangopay-tests.hs
@@ -5,6 +5,7 @@
 
 import Test.Framework
 
+import {-@ HTF_TESTS @-} Web.MangoPay.SimpleTest
 import {-@ HTF_TESTS @-} Web.MangoPay.AccessTest
 import {-@ HTF_TESTS @-} Web.MangoPay.UsersTest
 import {-@ HTF_TESTS @-} Web.MangoPay.WalletsTest