diff --git a/plinth/modules/matrixsynapse/templates/matrix-synapse.html b/plinth/modules/matrixsynapse/templates/matrix-synapse.html
index 55323839d..9a4b832ae 100644
--- a/plinth/modules/matrixsynapse/templates/matrix-synapse.html
+++ b/plinth/modules/matrixsynapse/templates/matrix-synapse.html
@@ -36,12 +36,13 @@
 
   {% if not has_valid_certificate %}
     <div class="alert alert-warning" role="alert">
+      {% url 'letsencrypt:index' as letsencrypt_url %}
       {% blocktrans %}
         The configured domain name is using a self-signed certificate.
-        Federation with other Matrix Synapse instances requires a valid TLS certificate.
-        Please go to <a href="/plinth/sys/letsencrypt">Let's Encrypt</a> to obtain one.
+        Federation with other Matrix Synapse instances requires a valid TLS
+        certificate. Please go to <a href="{{ letsencrypt_url }}">Let's
+        Encrypt</a> to obtain one.
       {% endblocktrans %}
     </div>
   {% endif %}
 {% endblock %}
-