diff --git a/backends/GenerateC.hs b/backends/GenerateC.hs
index 1c06bd5..5cf34f8 100644
--- a/backends/GenerateC.hs
+++ b/backends/GenerateC.hs
@@ -1105,9 +1105,10 @@ cgenInputItem c (A.InVariable m v)
                  call genBytesIn m t (Right v)
                  tell [");"]
 
-cgenOutputItem :: A.Variable -> A.OutputItem -> CGen ()
-cgenOutputItem c (A.OutCounted m ce ae)
-    =  do call genOutputItem c (A.OutExpression m ce)
+cgenOutputItem :: A.Type -> A.Variable -> A.OutputItem -> CGen ()
+cgenOutputItem _ c (A.OutCounted m ce ae)
+    =  do tce <- astTypeOf ce
+          call genOutputItem tce c (A.OutExpression m ce)
           t <- astTypeOf ae
           case ae of
             A.ExprVariable m v ->
@@ -1121,12 +1122,8 @@ cgenOutputItem c (A.OutCounted m ce ae)
                  tell ["*"]
                  call genBytesIn m subT (Right v)
                  tell [");"]
-cgenOutputItem c (A.OutExpression m e)
-    =  do t <- astTypeOf c
-          let innerT = case t of
-                A.Chan _ t' -> t'
-                A.ChanEnd _ _ t' -> t'
-          case (innerT, e) of
+cgenOutputItem innerT c (A.OutExpression m e)
+    =     case (innerT, e) of
             (A.Int, _) ->
               do tell ["ChanOutInt(wptr,"]
                  call genVariable c
@@ -1564,7 +1561,9 @@ cgenProcess :: A.Process -> CGen ()
 cgenProcess p = case p of
   A.Assign m vs es -> call genAssign m vs es
   A.Input m c im -> call genInput c im
-  A.Output m c ois -> call genOutput c ois
+  A.Output m c ois ->
+    do Left ts <- protocolItems c
+       call genOutput c $ zip ts ois
   A.OutputCase m c t ois -> call genOutputCase c t ois
   A.Skip m -> tell ["/* skip */\n"]
   A.Stop m -> call genStop m "STOP process"
@@ -1641,8 +1640,8 @@ cgenGetTime v
 
 --}}}
 --{{{  output
-cgenOutput :: A.Variable -> [A.OutputItem] -> CGen ()
-cgenOutput c ois = sequence_ $ map (call genOutputItem c) ois
+cgenOutput :: A.Variable -> [(A.Type, A.OutputItem)] -> CGen ()
+cgenOutput c tois = sequence_ [call genOutputItem t c oi | (t, oi) <- tois]
 
 cgenOutputCase :: A.Variable -> A.Name -> [A.OutputItem] -> CGen ()
 cgenOutputCase c tag ois
@@ -1657,7 +1656,10 @@ cgenOutputCase c tag ois
           tell ["_"]
           genName proto
           tell [");"]
-          call genOutput c ois
+          Right ps <- protocolItems c
+          let ts = fromMaybe (error "genOutputCase unknown tag")
+                     $ lookup tag ps
+          call genOutput c $ zip ts ois
 --}}}
 --{{{  stop
 cgenStop :: Meta -> String -> CGen ()
diff --git a/backends/GenerateCBased.hs b/backends/GenerateCBased.hs
index a04a325..4af98d7 100644
--- a/backends/GenerateCBased.hs
+++ b/backends/GenerateCBased.hs
@@ -145,11 +145,11 @@ data GenOps = GenOps {
     genMissingC :: CGen String -> CGen (),
     genMonadic :: Meta -> A.MonadicOp -> A.Expression -> CGen (),
     -- | Generates an output statement.
-    genOutput :: A.Variable -> [A.OutputItem] -> CGen (),
+    genOutput :: A.Variable -> [(A.Type, A.OutputItem)] -> CGen (),
     -- | Generates an output statement for a tagged protocol.
     genOutputCase :: A.Variable -> A.Name -> [A.OutputItem] -> CGen (),
     -- | Generates an output for an individual item.
-    genOutputItem :: A.Variable -> A.OutputItem -> CGen (),
+    genOutputItem :: A.Type -> A.Variable -> A.OutputItem -> CGen (),
     -- | Generates a loop that maps over every element in a (potentially multi-dimensional) array
     genOverArray :: Meta -> A.Variable -> (SubscripterFunction -> Maybe (CGen ())) -> CGen (),
     genPar :: A.ParMode -> A.Structured A.Process -> CGen (),
diff --git a/backends/GenerateCPPCSP.hs b/backends/GenerateCPPCSP.hs
index 9741655..81e43f9 100644
--- a/backends/GenerateCPPCSP.hs
+++ b/backends/GenerateCPPCSP.hs
@@ -322,8 +322,8 @@ cppgenInputItem c dest
                        genPoint v
                        tell ["));"]
 
-cppgenOutputItem :: A.Variable -> A.OutputItem -> CGen ()
-cppgenOutputItem chan item
+cppgenOutputItem :: A.Type -> A.Variable -> A.OutputItem -> CGen ()
+cppgenOutputItem _ chan item
   = case item of
       (A.OutCounted m (A.ExprVariable _ cv) (A.ExprVariable _ av)) -> (sendBytes cv) >> (sendBytes av)
       (A.OutExpression _ (A.ExprVariable _ sv)) ->
@@ -380,7 +380,7 @@ cppgenOutputCase c tag ois
           tell ["_"]
           genName proto
           tell [");"]
-          call genOutput c ois
+          call genOutput c $ zip (repeat undefined) ois
 
 
 -- | We use the process wrappers here, in order to execute the functions in parallel.
diff --git a/backends/GenerateCTest.hs b/backends/GenerateCTest.hs
index fae1a9a..4aca917 100644
--- a/backends/GenerateCTest.hs
+++ b/backends/GenerateCTest.hs
@@ -1144,9 +1144,11 @@ testOutput = TestList
    testOutputItem' :: Int -> String -> String -> A.OutputItem -> A.Type -> A.Type -> Test
    testOutputItem' n eC eCPP oi t ct = TestList
      [
-       testBothS ("testOutput " ++ show n) (hashIs "(&c)" eC) (hashIs "(&c)->writer()" eCPP) (over (tcall2 genOutputItem (A.Variable emptyMeta $ simpleName "c") oi))
+       testBothS ("testOutput " ++ show n) (hashIs "(&c)" eC) (hashIs "(&c)->writer()" eCPP)
+         (over (tcall3 genOutputItem A.Int64 (A.Variable emptyMeta $ simpleName "c") oi))
          (state $ A.Chan)
-       ,testBothS ("testOutput [out] " ++ show n) (hashIs "c" eC) (hashIs "c" eCPP) (over (tcall2 genOutputItem (A.Variable emptyMeta $ simpleName "c") oi))
+       ,testBothS ("testOutput [out] " ++ show n) (hashIs "c" eC) (hashIs "c" eCPP)
+         (over (tcall3 genOutputItem A.Int64 (A.Variable emptyMeta $ simpleName "c") oi))
          (state $ A.ChanEnd A.DirOutput)
      ]
      where
@@ -1167,7 +1169,7 @@ testOutput = TestList
               defineName chanOut $ simpleDefDecl "cOut" (A.ChanEnd A.DirOutput (A.ChanAttributes False False) $ A.UserProtocol foo)
    overOutput, overOutputItem, over :: Override
    overOutput = local $ \ops -> ops {genOutput = override2 caret}
-   overOutputItem = local $ \ops -> ops {genOutputItem = override2 caret}
+   overOutputItem = local $ \ops -> ops {genOutputItem = override3 caret}
    over = local $ \ops -> ops {genBytesIn = override3 caret}
 
 testBytesIn :: Test