diff --git a/__tests__/response/back.js b/__tests__/response/back.js
new file mode 100644
index 000000000..cd28fd94f
--- /dev/null
+++ b/__tests__/response/back.js
@@ -0,0 +1,32 @@
+'use strict'
+
+const assert = require('assert')
+const context = require('../../test-helpers/context')
+
+describe('ctx.back([alt])', () => {
+  it('should redirect to Referrer', () => {
+    const ctx = context()
+    ctx.req.headers.referrer = '/login'
+    ctx.back()
+    assert.equal(ctx.response.header.location, '/login')
+  })
+
+  it('should redirect to Referer', () => {
+    const ctx = context()
+    ctx.req.headers.referer = '/login'
+    ctx.back()
+    assert.equal(ctx.response.header.location, '/login')
+  })
+
+  it('should default to alt', () => {
+    const ctx = context()
+    ctx.back('/index.html')
+    assert.equal(ctx.response.header.location, '/index.html')
+  })
+
+  it('should default redirect to /', () => {
+    const ctx = context()
+    ctx.back()
+    assert.equal(ctx.response.header.location, '/')
+  })
+})
diff --git a/lib/response.js b/lib/response.js
index a4e18489e..5cda6ce60 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -18,7 +18,7 @@ const only = require('./only.js')
 const util = require('util')
 const encodeUrl = require('encodeurl')
 const Stream = require('stream')
-const deprecate = require('depd')('koa');
+const deprecate = require('depd')('koa')
 
 /**
  * Prototype.
@@ -296,8 +296,8 @@ module.exports = {
     // location
     if (url === 'back') {
       deprecate('Special-cased string "back" through redirect will be removed in v3, ' +
-        'consider migrating usage to ctx.back() instead.');
-      url = this.ctx.get('Referrer') || alt || '/';
+        'consider migrating usage to ctx.back() instead.')
+      url = this.ctx.get('Referrer') || alt || '/'
     }
     if (/^https?:\/\//i.test(url)) {
       // formatting url again avoid security escapes
@@ -334,9 +334,9 @@ module.exports = {
    * @api public
    */
 
-  back(alt) {
-    const url = this.ctx.get('Referrer') || alt || '/';
-    this.redirect(url);
+  back (alt) {
+    const url = this.ctx.get('Referrer') || alt || '/'
+    this.redirect(url)
   },
 
   /**
diff --git a/test/response/back.js b/test/response/back.js
deleted file mode 100644
index e6c30c378..000000000
--- a/test/response/back.js
+++ /dev/null
@@ -1,33 +0,0 @@
-
-'use strict';
-
-const assert = require('assert');
-const context = require('../helpers/context');
-
-describe('ctx.back([alt])', () => {
-  it('should redirect to Referrer', () => {
-    const ctx = context();
-    ctx.req.headers.referrer = '/login';
-    ctx.back();
-    assert.equal(ctx.response.header.location, '/login');
-  });
-
-  it('should redirect to Referer', () => {
-    const ctx = context();
-    ctx.req.headers.referer = '/login';
-    ctx.back();
-    assert.equal(ctx.response.header.location, '/login');
-  });
-
-  it('should default to alt', () => {
-    const ctx = context();
-    ctx.back('/index.html');
-    assert.equal(ctx.response.header.location, '/index.html');
-  });
-
-  it('should default redirect to /', () => {
-    const ctx = context();
-    ctx.back();
-    assert.equal(ctx.response.header.location, '/');
-  });
-});