diff --git a/ad-server/templates/smb.conf.j2 b/ad-server/templates/smb.conf.j2
index 28331af0e2ae7250d2e302c7fbb5b530c0054c80..3bd4725fd8292b4444a31f1eec4bd6c4fea4f8ab 100644
--- a/ad-server/templates/smb.conf.j2
+++ b/ad-server/templates/smb.conf.j2
@@ -19,6 +19,7 @@
         kdc:renewal lifetime = {{ renewal_lifetime }}
 
         tls enabled = yes
+        tls cafile = /etc/ssl/certs/rwth_chain.pem
         tls keyfile = {{smb_tls_key}}
         tls certfile = {{smb_tls_cert}}