diff --git a/overlay/etc/templates/config.php.tmpl b/overlay/etc/templates/config.php.tmpl
index 1594dc0..2f36275 100644
--- a/overlay/etc/templates/config.php.tmpl
+++ b/overlay/etc/templates/config.php.tmpl
@@ -111,10 +111,10 @@ define('LDAP_BIND_TYPE', '{{ getenv "KANBOARD_LDAP_BIND_TYPE" "anonymous" }}');
 
 // LDAP username to use with proxy mode
 // LDAP username pattern to use with user mode
-define('LDAP_USERNAME', {{ getenv "KANBOARD_LDAP_USERNAME" "null" }});
+define('LDAP_USERNAME', '{{ getenv "KANBOARD_LDAP_USERNAME" }}');
 
 // LDAP password to use for proxy mode
-define('LDAP_PASSWORD', {{ getenv "KANBOARD_LDAP_PASSWORD" "null" }});
+define('LDAP_PASSWORD', '{{ getenv "KANBOARD_LDAP_PASSWORD" }}');
 
 // LDAP DN for users
 // Example for ActiveDirectory: CN=Users,DC=kanboard,DC=local