diff --git a/_layouts/default.html b/_layouts/default.html
index c47c612..86f7043 100644
--- a/_layouts/default.html
+++ b/_layouts/default.html
@@ -61,6 +61,6 @@ layout: base
     <a href="/feed.xml">Atom</a> |
     <span id="commit-id" class="build-revision"><a
             href="{{ site.github.repository_url }}/commit/{{ site.github.build_revision | default: site.env.GITHUB_SHA }}">
-        #{{ site.github.build_revision | truncate: 7, "" }}
+        #{{ site.github.build_revision | default: site.env.GITHUB_SHA | truncate: 7, "" }}
     </a></span>
 </p>