diff --git a/horizon/openstack-dashboard.conf b/horizon/openstack-dashboard.conf
index 2dc4b2c..dfa7b5b 100644
--- a/horizon/openstack-dashboard.conf
+++ b/horizon/openstack-dashboard.conf
@@ -12,6 +12,7 @@
     SSLEngine On
     SSLCertificateFile "/certs/merlin.hpc.rug.nl.crt"
     SSLCertificateKeyFile "/certs/merlin.hpc.rug.nl.key"
+    SSLCACertificateFile "/certs/DigiCertCA.crt"
     SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown
 
     # HTTP Strict Transport Security (HSTS) enforces that all communications