diff --git a/doc/guide/preamble.sdf b/doc/guide/preamble.sdf
index 3974a5f149..17220f05e7 100644
--- a/doc/guide/preamble.sdf
+++ b/doc/guide/preamble.sdf
@@ -103,7 +103,7 @@ OpenLDAP|OpenLDAP|http://www.openldap.org/
 OLF|OpenLDAP Foundation|http://www.openldap.org/foundation/
 OLP|OpenLDAP Project|http://www.openldap.org/project/
 UM|University of Michigan|http://www.umich.edu/
-UMLDAP|University of Michigan LDAP|http://www.umich.edu/~dirsvcs/ldap/
+UMLDAP|University of Michigan LDAP|http://www.umich.edu/~dirsvcs/ldap/ldap.html
 IANA|Internet Assigned Numbers Authority|http://www.iana.org/
 IAB|Internet Architecture Board|http://www.iab.org/
 IETF|Internet Engineering Task Force|http://www.ietf.org/