diff --git a/common/Types.hs b/common/Types.hs
index b344003..4c66a9c 100644
--- a/common/Types.hs
+++ b/common/Types.hs
@@ -271,6 +271,7 @@ typeOfVariable (A.DirectedVariable m dir v)
              if dir == dir'
                then return t
                else dieP m $ "Attempted to reverse direction of a channel-end"
+           A.ChanDataType _ a b -> return $ A.ChanDataType dir a b
            A.Infer -> return $ A.ChanEnd dir A.Unshared A.Infer
            _ -> diePC m $ formatCode "Direction specified on non-channel variable of type: %" t
 typeOfVariable (A.VariableSizes m v)
@@ -588,6 +589,7 @@ isCommunicableType (A.Array _ t) = isCommunicableType t
 isCommunicableType (A.List t) = isCommunicableType t
 isCommunicableType (A.Record _) = True
 isCommunicableType (A.Mobile _) = True
+isCommunicableType (A.ChanDataType {}) = True
 isCommunicableType t = isScalarType t
 
 -- | Types that support 'Size' and subscripting.
diff --git a/frontends/OccamTypes.hs b/frontends/OccamTypes.hs
index 410b0b6..941fd74 100644
--- a/frontends/OccamTypes.hs
+++ b/frontends/OccamTypes.hs
@@ -1340,6 +1340,7 @@ checkVariables = checkDepthM doVariable
                 A.Chan _ _ -> ok
                 A.Array _ (A.ChanEnd oldDir _ _) -> checkDir oldDir
                 A.Array _ (A.Chan _ _) -> ok
+                A.ChanDataType oldDir _ _ -> checkDir oldDir
                 _ -> diePC m $ formatCode "Direction specified on non-channel variable of type: %" t
       where
         checkDir oldDir
@@ -1429,10 +1430,11 @@ checkSpecTypes = checkDepthM doSpecType
     doSpecType (A.Is m am t (A.ActualClaim v))
         =  do tv <- astTypeOf v
               checkAbbrev m A.Abbrev am
-              checkType (findMeta v) t tv
               case tv of
-                A.ChanEnd _ A.Shared _ -> return ()
-                A.ChanDataType _ A.Shared _ -> return ()
+                A.ChanEnd a A.Shared b ->
+                  checkType (findMeta v) t (A.ChanEnd a A.Unshared b)
+                A.ChanDataType a A.Shared b ->
+                  checkType (findMeta v) t (A.ChanDataType a A.Unshared b)
                 _ -> dieP m "Expected shared channel end in claim"
     doSpecType (A.Is m am rawT (A.ActualChannelArray cs))
         =  do t <- resolveUserType m rawT