diff --git a/src/Network/Wai/Middleware/Cache.hs b/src/Network/Wai/Middleware/Cache.hs
--- a/src/Network/Wai/Middleware/Cache.hs
+++ b/src/Network/Wai/Middleware/Cache.hs
@@ -13,7 +13,8 @@
 import           Data.IORef
 import           Network.Wai              (Middleware, Request, Response,
                                            requestBody, responseToStream,
-                                           mapResponseHeaders)
+                                           responseStatus, mapResponseHeaders)
+import Network.HTTP.Types.Status (statusCode)
 
 --------------------------------------------------------------------------------
 -- | The data structure that should contains everything you need to create
@@ -87,10 +88,15 @@
                      -> Response
                      -> IO b
 addToCacheAndRespond cb sendResponse req key r = do
-  cacheVal <- responseToCacheVal cb r
-  addToCache cb (cacheContainer cb) key cacheVal
-  actionOnCacheMiss cb req r
-  sendResponse (cacheValToResponse cb cacheVal)
+  let code = statusCode (responseStatus r)
+  if (code >= 200) && (code < 400)
+    then do
+      cacheVal <- responseToCacheVal cb r
+      addToCache cb (cacheContainer cb) key cacheVal
+      actionOnCacheMiss cb req r
+      sendResponse (cacheValToResponse cb cacheVal)
+    else
+      sendResponse r
 
 getRequestBody :: Request -> IO (Request, S8.ByteString)
 getRequestBody req = do
diff --git a/wai-middleware-caching.cabal b/wai-middleware-caching.cabal
--- a/wai-middleware-caching.cabal
+++ b/wai-middleware-caching.cabal
@@ -1,5 +1,5 @@
 name:                wai-middleware-caching
-version:             0.1.0.1
+version:             0.1.0.2
 synopsis:            WAI Middleware to cache things
 description:         Please see README.md
 homepage:            http://github.com/yogsototh/wai-middleware-caching/tree/master/wai-middleware-caching#readme
@@ -20,6 +20,7 @@
                      , blaze-builder
                      , bytestring
                      , wai >= 3.0
+                     , http-types
   default-language:    Haskell2010
 
 test-suite wai-middleware-caching-test