diff --git a/Network/Wai/Application/Static.hs b/Network/Wai/Application/Static.hs
--- a/Network/Wai/Application/Static.hs
+++ b/Network/Wai/Application/Static.hs
@@ -217,9 +217,7 @@
         return $ fileToResponse file H.status200 headers
 
     response NotModified =
-            return $ W.responseLBS H.status304
-                        [ ("Content-Type", "text/plain")
-                        ] "Not Modified"
+            return $ W.responseLBS H.status304 [] ""
 
     response (SendContent mt lbs) = do
             -- TODO: set caching headers
diff --git a/wai-app-static.cabal b/wai-app-static.cabal
--- a/wai-app-static.cabal
+++ b/wai-app-static.cabal
@@ -1,5 +1,5 @@
 name:            wai-app-static
-version:         1.3.1.2
+version:         1.3.1.3
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>