diff --git a/resources/template/common/web/sitemap_html.tmpl b/resources/template/common/web/sitemap_html.tmpl
index b654671f..08134a6d 100644
--- a/resources/template/common/web/sitemap_html.tmpl
+++ b/resources/template/common/web/sitemap_html.tmpl
@@ -135,7 +135,7 @@
             <div class="clear"></div>
             <li>
                 <div class="T1 pull-left"><a href="{{.blog_url}}" title="{{.blog_title}}">{{.blog_title}}</a></div>
-                <div class="T2 pull-right">{{unix_milli_time_format "2006-01-02" .options.birthday}} </div>
+                <div class="T2 pull-right">{{unix_milli_time_format "2006-01-02" (int64 .options.birthday)}} </div>
                 <div class="T3 pull-right">daily</div>
                 <div class="T4 pull-right">1</div>
             </li>
diff --git a/resources/template/common/web/sitemap_xml.tmpl b/resources/template/common/web/sitemap_xml.tmpl
index 228ef82c..43192ba4 100644
--- a/resources/template/common/web/sitemap_xml.tmpl
+++ b/resources/template/common/web/sitemap_xml.tmpl
@@ -3,7 +3,7 @@
     <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
         <url>
             <loc>{{.blog_url}}</loc>
-            <lastmod>{{unix_milli_time_format "2006-01-02T15:04:05Z07:00" .options.birthday}}</lastmod>
+            <lastmod>{{unix_milli_time_format "2006-01-02T15:04:05Z07:00" (int64 .options.birthday)}}</lastmod>
         </url>
         {{if (gt (len .posts) 0)}}
             {{range $post := .posts}}