diff --git a/Doc/tools/templates/customsourcelink.html b/Doc/tools/templates/customsourcelink.html
index 42172909cae438..fca44e9163cac7 100644
--- a/Doc/tools/templates/customsourcelink.html
+++ b/Doc/tools/templates/customsourcelink.html
@@ -4,7 +4,7 @@ <h3>{{ _('This Page') }}</h3>
     <ul class="this-page-menu">
       <li><a href="{{ pathto('bugs') }}">{% trans %}Report a Bug{% endtrans %}</a></li>
       <li>
-        <a href="https://github.com/python/cpython/blob/master/Doc/{{ sourcename|replace('txt', 'rst') }}"
+        <a href="https://github.com/python/cpython/blob/master/Doc/{{ sourcename|replace('.rst.txt', '.rst') }}"
             rel="nofollow">{{ _('Show Source') }}
         </a>
       </li>