diff --git a/src/etc/inc/interfaces.inc b/src/etc/inc/interfaces.inc
index 24d4df33f..b7f40157b 100644
--- a/src/etc/inc/interfaces.inc
+++ b/src/etc/inc/interfaces.inc
@@ -1165,7 +1165,7 @@ EOD;
         } else {
             $mpdconf_arr[] = "set link mtu " . ($mtus[$pid] - 8);
         }
-        $mrus = !empty($ppp['mtu']) ? explode(',', $ppp['mru']) : null;
+        $mrus = !empty($ppp['mru']) ? explode(',', $ppp['mru']) : null;
         if (!empty($mrus[$pid])) {
             $mpdconf_arr[] = "set link mru {$mrus[$pid]}";
         }