diff --git a/Network/DNS/Cache.hs b/Network/DNS/Cache.hs
--- a/Network/DNS/Cache.hs
+++ b/Network/DNS/Cache.hs
@@ -19,7 +19,7 @@
   ) where
 
 import Control.Applicative ((<$>))
-import Control.Concurrent (threadDelay, forkIO)
+import Control.Concurrent (threadDelay, forkIO, killThread)
 import Control.Concurrent.Async (async, waitAnyCancel)
 import Control.Exception (bracket)
 import Control.Monad (forever, void)
@@ -78,8 +78,7 @@
     activeref <- S.newActiveRef
     lvar <- S.newConcVar
     let cache = DNSCache seeds n cacheref activeref lvar maxcon minttl maxttl negttl
-    void . forkIO $ prune cacheref
-    func cache
+    bracket (forkIO $ prune cacheref) killThread (const $ func cache)
   where
     maxcon = maxConcurrency conf
     minttl = minTTL conf
@@ -121,7 +120,7 @@
 resolveCache _ dom
   | isIPAddr dom       = Just . Right . Numeric <$> return (tov4 dom)
   where
-    tov4 = read . BS.unpack
+    tov4 = toHostAddress . read . BS.unpack
 resolveCache cache dom = do
     (_, mx) <- lookupPSQ cache dom
     case mx of
@@ -136,7 +135,7 @@
 resolve _     dom
   | isIPAddr dom            = return $ Right $ Numeric $ tov4 dom
   where
-    tov4 = read . BS.unpack
+    tov4 = toHostAddress . read . BS.unpack
 resolve cache dom = do
     (key,mx) <- lookupPSQ cache dom
     case mx of
@@ -158,10 +157,12 @@
                         Right []    -> insertNegative cache key UnexpectedRDATA
                         Right addrs -> insertPositive cache key addrs
                     S.deleteActiveRef key activeref
-                    S.tell avar res
+                    S.tell avar (toHit res)
                     return res
   where
     activeref = cacheActiveRef cache
+    toHit (Right (Resolved addr)) = Right (Hit addr)
+    toHit x                       = x
 
 insertPositive :: DNSCache -> Key -> [(HostAddress, TTL)]
                -> IO (Either DNSError Result)
diff --git a/Network/DNS/Cache/Value.hs b/Network/DNS/Cache/Value.hs
--- a/Network/DNS/Cache/Value.hs
+++ b/Network/DNS/Cache/Value.hs
@@ -13,7 +13,7 @@
     return $! Right val
   where
     !siz = length addrs
-    !next = adjust 0 siz
+    !next = adjust 0 (siz-1)
     !arr = listArray (0,siz-1) addrs
 
 rotate :: Value -> IO HostAddress
@@ -25,4 +25,4 @@
 
 adjust :: Int -> Int -> Int
 adjust i 0 = i
-adjust i n = let !x = (i + 1) `mod` n in x
+adjust i n = let !x = (i + 1) `mod` (n + 1) in x
diff --git a/concurrent-dns-cache.cabal b/concurrent-dns-cache.cabal
--- a/concurrent-dns-cache.cabal
+++ b/concurrent-dns-cache.cabal
@@ -1,5 +1,5 @@
 Name:                   concurrent-dns-cache
-Version:                0.0.0
+Version:                0.0.1
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3
@@ -55,6 +55,7 @@
   Hs-Source-Dirs:       test
   Type:                 exitcode-stdio-1.0
   Build-Depends:        base >= 4 && < 5
-                      , dns
+                      , async
                       , concurrent-dns-cache
+                      , dns
                       , hspec
diff --git a/test/CacheSpec.hs b/test/CacheSpec.hs
--- a/test/CacheSpec.hs
+++ b/test/CacheSpec.hs
@@ -2,10 +2,11 @@
 
 module CacheSpec where
 
-import Test.Hspec
+import Control.Concurrent.Async (concurrently)
 import Network.DNS hiding (lookup)
 import Network.DNS.Cache
 import Prelude hiding (lookup)
+import Test.Hspec
 
 cacheConf :: DNSCacheConf
 cacheConf = DNSCacheConf {
@@ -42,3 +43,8 @@
         resolveCache cache dom `shouldReturn` Just (Left err)
         lookupCache  cache dom `shouldReturn` Nothing
         lookup       cache dom `shouldReturn` Nothing
+    it "waits for another query for the same domain" $ withDNSCache cacheConf $ \cache -> do
+        let dom = "www.example.com"
+            addr = 2010691677
+        (res1,res2) <- concurrently (resolve cache dom) (resolve cache dom)
+        [res1,res2] `shouldContain` [Right (Resolved addr),Right (Hit addr)]