diff --git a/src/Disco/Interpret/CESK.hs b/src/Disco/Interpret/CESK.hs
index a64fbec3..be2f8431 100644
--- a/src/Disco/Interpret/CESK.hs
+++ b/src/Disco/Interpret/CESK.hs
@@ -182,8 +182,8 @@ step cesk = case cesk of
       True -> do 
          cell <- allocateValue (VTrie T.empty)
          -- cell <- allocateValue (VMap M.empty)
-         return $ Out (VClo [] (Just cell) e xs body) k
-      False -> return $ Out (VClo [] Nothing e xs body) k
+         return $ Out (VClo (Just (cell,[])) e xs body) k
+      False -> return $ Out (VClo Nothing e xs body) k
 
   (In (CApp c1 c2) e k) -> return $ In c1 e (FArg e c2 : k)
   (In (CType ty) _ k) -> return $ Out (VType ty) k
@@ -209,18 +209,18 @@ step cesk = case cesk of
 
   (Out v (FMemo n sv : k)) -> memoSet n sv v *> (return $ Out v k)
 
-  (Out v (FApp (VClo mem mi e [x] b) : k)) -> case mi of
+  (Out v (FApp (VClo mi e [x] b) : k)) -> case mi of
    Nothing -> return $ In b (Ctx.insert (localName x) v e) k
-   Just n -> do
+   Just (n,mem) -> do
       let sv = toSimpleValue $ foldr VPair VUnit (v : mem)
       mv <- memoLookup n sv
       case mv of
          Nothing -> return $ In b (Ctx.insert (localName x) v e) (FMemo n sv : k)
          Just v' -> return $ Out v' k
 
-  (Out v (FApp (VClo mem mi e (x : xs) b) : k)) -> case mi of
-   Just _ -> return $ Out (VClo (v : mem) mi (Ctx.insert (localName x) v e) xs b) k
-   Nothing -> return $ Out (VClo mem mi (Ctx.insert (localName x) v e) xs b) k
+  (Out v (FApp (VClo mi e (x : xs) b) : k)) -> case mi of
+   Just (n,mem) -> return $ Out (VClo (Just (n,v:mem)) (Ctx.insert (localName x) v e) xs b) k
+   Nothing -> return $ Out (VClo mi (Ctx.insert (localName x) v e) xs b) k
 
 
 
@@ -229,8 +229,8 @@ step cesk = case cesk of
   -- Annoying to repeat this code, not sure of a better way.
   -- The usual evaluation order (function then argument) doesn't work when
   -- we're applying a test function to randomly generated values.
-  (Out (VClo _ _ e [x] b) (FArgV v : k)) -> return $ In b (Ctx.insert (localName x) v e) k
-  (Out (VClo mem mi e (x : xs) b) (FArgV v : k)) -> return $ Out (VClo mem mi (Ctx.insert (localName x) v e) xs b) k
+  (Out (VClo _ e [x] b) (FArgV v : k)) -> return $ In b (Ctx.insert (localName x) v e) k
+  (Out (VClo mi e (x : xs) b) (FArgV v : k)) -> return $ Out (VClo mi (Ctx.insert (localName x) v e) xs b) k
   (Out (VConst op) (FArgV v : k)) -> appConst k op v
   (Out (VFun f) (FArgV v : k)) -> return $ Out (f v) k
   (Out (VRef n) (FForce : k)) -> do
diff --git a/src/Disco/Value.hs b/src/Disco/Value.hs
index 84a36dc0..5661ef1c 100644
--- a/src/Disco/Value.hs
+++ b/src/Disco/Value.hs
@@ -134,7 +134,7 @@ data Value where
   VPair :: Value -> Value -> Value
   -- | A closure, i.e. a function body together with its
   --   environment.
-  VClo :: [Value] -> Maybe Int -> Env -> [Name Core] -> Core -> Value
+  VClo :: Maybe (Int,[Value]) -> Env -> [Name Core] -> Core -> Value
   -- | A disco type can be a value.  For now, there are only a very
   --   limited number of places this could ever show up (in
   --   particular, as an argument to @enumerate@ or @count@).
@@ -168,7 +168,7 @@ data Value where
   --   property when the key type is finite.
   VMap :: Map SimpleValue Value -> Value
 
-  VTrie :: T.TrieMap M.Map SimpleValue Value -> Value
+  VTrie :: T.TrieMap Map SimpleValue Value -> Value
 
   VGen :: StdGen -> Value
   deriving (Show)