diff --git a/lib/hs/src/Thrift/Protocol/Compact.hs b/lib/hs/src/Thrift/Protocol/Compact.hs
index c3bd22d..a329f4e 100644
--- a/lib/hs/src/Thrift/Protocol/Compact.hs
+++ b/lib/hs/src/Thrift/Protocol/Compact.hs
@@ -60,6 +60,7 @@
 version     = 0x01
 versionMask = 0x1f -- 0001 1111
 typeMask    = 0xe0 -- 1110 0000
+typeBits    = 0x07 -- 0000 0111
 typeShiftAmount :: Int
 typeShiftAmount = 5
 
@@ -81,7 +82,7 @@
       w <- fromIntegral <$> P.anyWord8
       let ver = w .&. versionMask 
       when (ver /= version) $ error "Bad Protocol version"
-      let typ = (w `shiftR` typeShiftAmount) .&. 0x03
+      let typ = (w `shiftR` typeShiftAmount) .&. typeBits
       seqId <- parseVarint zigZagToI32
       TString name <- parseCompactValue T_STRING
       return (decodeUtf8 name, toEnum $ fromIntegral $ typ, seqId)
diff --git a/lib/hs/src/Thrift/Types.hs b/lib/hs/src/Thrift/Types.hs
index b014ac6..b90c42c 100644
--- a/lib/hs/src/Thrift/Types.hs
+++ b/lib/hs/src/Thrift/Types.hs
@@ -113,17 +113,20 @@
     = M_CALL
     | M_REPLY
     | M_EXCEPTION
+    | M_ONEWAY
       deriving ( Eq, Show )
 
 instance Enum MessageType where
     fromEnum M_CALL      =  1
     fromEnum M_REPLY     =  2
     fromEnum M_EXCEPTION =  3
+    fromEnum M_ONEWAY    =  4
 
     toEnum 1 = M_CALL
     toEnum 2 = M_REPLY
     toEnum 3 = M_EXCEPTION
+    toEnum 4 = M_ONEWAY
     toEnum t = error $ "Invalid MessageType " ++ show t
 
 instance Arbitrary MessageType where
-  arbitrary = elements [M_CALL, M_REPLY, M_EXCEPTION]
+  arbitrary = elements [M_CALL, M_REPLY, M_EXCEPTION, M_ONEWAY]