diff --git a/src/Plugins/Mail.hs b/src/Plugins/Mail.hs
index 58431ce..2d0be37 100644
--- a/src/Plugins/Mail.hs
+++ b/src/Plugins/Mail.hs
@@ -49,18 +49,18 @@ instance Exec Mail where
         forM_ (zip ds vs) $ \(d, v) -> do
             s <- fmap (S.fromList . filter (not . isPrefixOf "."))
                     $ getDirectoryContents d
-            atomically $ modifyTVar v (S.union s)
+            atomically $ modifyTVarxm v (S.union s)
 
         changeLoop (mapM (fmap S.size . readTVar) vs) $ \ns ->
             cb . unwords $ [m ++ ":" ++  show n
                                     | (m, n) <- zip ts ns
                                     , n /= 0 ]
 
-modifyTVar :: TVar a -> (a -> a) -> STM ()
-modifyTVar v f = readTVar v >>= writeTVar v . f
+modifyTVarxm :: TVar a -> (a -> a) -> STM ()
+modifyTVarxm v f = readTVar v >>= writeTVar v . f
 
 handle :: TVar (Set String) -> Event -> IO ()
-handle v e = atomically $ modifyTVar v $ case e of
+handle v e = atomically $ modifyTVarxm v $ case e of
     Created  {} -> create
     MovedIn  {} -> create
     Deleted  {} -> delete
diff --git a/src/Plugins/Monitors/MPD.hs b/src/Plugins/Monitors/MPD.hs
index 60c3e48..757c1ca 100644
--- a/src/Plugins/Monitors/MPD.hs
+++ b/src/Plugins/Monitors/MPD.hs
@@ -102,5 +102,5 @@ showTime t = int2str minutes ++ ":" ++ int2str seconds
   where minutes = t `div` 60
         seconds = t `mod` 60
 
-int2str :: (Num a, Ord a) => a -> String
+int2str :: (Num a, Ord a, Show a) => a -> String
 int2str x = if x < 10 then '0':sx else sx where sx = show x