diff --git a/app.py b/app.py
index 27730a5..d6e7672 100755
--- a/app.py
+++ b/app.py
@@ -62,7 +62,8 @@
 
 def find_user_dn(server, uid):
     with Connection(server) as c:
-        c.search(CONF['ldap']['base'], "(uid=%s)" % uid, SUBTREE, attributes=['dn'])
+        search_filter = CONF['ldap']['search_filter'].replace('{uid}', uid)
+        c.search(CONF['ldap']['base'], "(%s)" % search_filter, SUBTREE, attributes=['dn'])
         return c.response[0]['dn'] if c.response else None
 
 
diff --git a/settings.ini b/settings.ini
index de06e08..d343305 100644
--- a/settings.ini
+++ b/settings.ini
@@ -5,6 +5,7 @@
 host = localhost
 port = 389
 base = ou=People,dc=example,dc=org
+search_filter = uid={uid}
 
 [server]
 server = auto