diff --git a/etc/inc/captiveportal.inc b/etc/inc/captiveportal.inc
index 31cc680470..28dab571e2 100644
--- a/etc/inc/captiveportal.inc
+++ b/etc/inc/captiveportal.inc
@@ -43,6 +43,7 @@
 /* include all configuration functions */
 require_once("config.inc");
 require_once("functions.inc");
+require_once("filter.inc");
 require_once("radius.inc");
 require_once("voucher.inc");