diff --git a/src/etc/inc/util.inc b/src/etc/inc/util.inc
index 14ac5ec5f..0bf6b85c2 100644
--- a/src/etc/inc/util.inc
+++ b/src/etc/inc/util.inc
@@ -1267,27 +1267,3 @@ function dhcp6c_duid_clear()
     /* clear the backup so that it will not be restored: */
     @unlink('/conf/dhcp6c_duid');
 }
-
-/**
- * check if interface is assigned
- * @param $interface technical interface name
- * @return string interface name (lan, wan, optX)
- */
-function is_interface_assigned($interface)
-{
-    global $config;
-
-    foreach (legacy_config_get_interfaces() as $if => $intf) {
-        if (isset($intf['if']) && $intf['if'] == $interface) {
-            return true;
-        }
-    }
-    if (isset($config['vlans']['vlan'])) {
-        foreach ($config['vlans']['vlan'] as $vlan) {
-            if ($vlan['if'] == $interface) {
-                return true;
-            }
-        }
-    }
-    return false;
-}