diff --git a/index.js b/index.js
index 1f51b1771..a63ed2cb6 100644
--- a/index.js
+++ b/index.js
@@ -5,6 +5,7 @@ const config = require('./config');
 
 const onerror = require('./middleware/onerror');
 const header = require('./middleware/header.js');
+const utf8 = require('./middleware/utf8');
 const memoryCache = require('./middleware/cache.js');
 const redisCache = require('koa-redis-cache');
 
@@ -24,22 +25,28 @@ app.use(onerror);
 // set header
 app.use(header);
 
+// fix incorrect `utf-8` characters
+app.use(utf8);
+
 // cache
 if (config.cacheType === 'memory') {
-    app.use(memoryCache({
-        expire: config.cacheExpire
-    }));
-}
-else if (config.cacheType === 'redis') {
-    app.use(redisCache({
-        expire: config.cacheExpire,
-        onerror: (e) => {
-            logger.error('cache error', e);
-        }
-    }));
+    app.use(
+        memoryCache({
+            expire: config.cacheExpire
+        })
+    );
+} else if (config.cacheType === 'redis') {
+    app.use(
+        redisCache({
+            expire: config.cacheExpire,
+            onerror: (e) => {
+                logger.error('cache error', e);
+            }
+        })
+    );
 }
 
 // router
 app.use(router.routes()).use(router.allowedMethods());
 
-app.listen(config.port);
\ No newline at end of file
+app.listen(config.port);
diff --git a/middleware/utf8.js b/middleware/utf8.js
new file mode 100644
index 000000000..cca1a34a8
--- /dev/null
+++ b/middleware/utf8.js
@@ -0,0 +1,6 @@
+// https://stackoverflow.com/questions/2507608/error-input-is-not-proper-utf-8-indicate-encoding-using-phps-simplexml-lo/40552083#40552083
+// https://stackoverflow.com/questions/1497885/remove-control-characters-from-php-string/1497928#1497928
+module.exports = async (ctx, next) => {
+    await next();
+    ctx.body = ctx.body.replace(/[\x00-\x1F\x7F]/g, '');
+};