diff --git a/src/core/fetch/ajax.js b/src/core/fetch/ajax.js
index 1824cc459..d311f46b7 100644
--- a/src/core/fetch/ajax.js
+++ b/src/core/fetch/ajax.js
@@ -45,7 +45,8 @@ export function get (url, hasBar = false) {
           const result = cache[url] = {
             content: target.response,
             opt: {
-              updatedAt: xhr.getResponseHeader('last-modified')
+              updatedAt: xhr.getResponseHeader('last-modified') ||
+                xhr.getResponseHeader('expires')
             }
           }
 
diff --git a/src/core/render/index.js b/src/core/render/index.js
index c4bd4201c..6c5581e4d 100644
--- a/src/core/render/index.js
+++ b/src/core/render/index.js
@@ -108,10 +108,12 @@ export function renderMixin (proto) {
     getAndActive('nav')
   }
 
-  proto._renderMain = function (text, opt) {
+  proto._renderMain = function (text, opt = {}) {
     callHook(this, 'beforeEach', text, result => {
       let html = this.isHTML ? result : markdown(result)
-      html = formatUpdated(html, opt.updatedAt, this.config.formatUpdated)
+      if (opt.updatedAt) {
+        html = formatUpdated(html, opt.updatedAt, this.config.formatUpdated)
+      }
 
       callHook(this, 'afterEach', html, text => renderMain.call(this, text))
     })