diff --git a/src/Vervis/Foundation.hs b/src/Vervis/Foundation.hs
index bb656dd..4e7bad9 100644
--- a/src/Vervis/Foundation.hs
+++ b/src/Vervis/Foundation.hs
@@ -193,12 +193,15 @@ instance Yesod App where
                 defaultCsrfHeaderName
                 defaultCsrfParamName
           )
-        . ( \ handler -> do
-                host <- getsYesod $ appInstanceHost . appSettings
-                bs <- lookupHeaders hHost
-                case bs of
-                    [b] | b == encodeUtf8 host -> handler
-                    _ -> invalidArgs [hostMismatch host bs]
+        . ( \ handler ->
+                if developmentMode
+                    then handler
+                    else do
+                        host <- getsYesod $ appInstanceHost . appSettings
+                        bs <- lookupHeaders hHost
+                        case bs of
+                            [b] | b == encodeUtf8 host -> handler
+                            _ -> invalidArgs [hostMismatch host bs]
           )
         . defaultYesodMiddleware
         where
diff --git a/src/Vervis/Settings.hs b/src/Vervis/Settings.hs
index 55740e5..a2882ca 100644
--- a/src/Vervis/Settings.hs
+++ b/src/Vervis/Settings.hs
@@ -164,14 +164,17 @@ data AppSettings = AppSettings
     , appHighlightStyle           :: Text
     }
 
+developmentMode :: Bool
+developmentMode =
+#if DEVELOPMENT
+    True
+#else
+    False
+#endif
+
 instance FromJSON AppSettings where
     parseJSON = withObject "AppSettings" $ \ o -> do
-        let defaultDev =
-#if DEVELOPMENT
-                True
-#else
-                False
-#endif
+        let defaultDev = developmentMode
         appStaticDir              <- o .: "static-dir"
         appDatabaseConf           <- o .: "database"
         appMaxInstanceKeys        <- o .:? "max-instance-keys"