diff --git a/src/messenger/webim/b.php b/src/messenger/webim/b.php
index 7af33528..4780c50f 100644
--- a/src/messenger/webim/b.php
+++ b/src/messenger/webim/b.php
@@ -58,6 +58,9 @@ $image_postfix = has_online_operators($groupid) ? "on" : "off";
 $filename = "locales/${lang}/button/${image}_${image_postfix}.gif";
 
 $fp = fopen($filename, 'rb') or die("no image");
+header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
+header("Cache-Control: no-store, no-cache, must-revalidate");
+header("Pragma: no-cache");
 header("Content-Type: image/gif");
 header("Content-Length: ".filesize($filename));
 if(function_exists('fpassthru')){