diff --git a/helper/networktool.php b/helper/networktool.php
index 633f54f..18212e2 100644
--- a/helper/networktool.php
+++ b/helper/networktool.php
@@ -131,7 +131,7 @@ if(!is_fn("get_network_outbound_addr")) {
 if(!is_fn("detect_perf_agent")) {
     function detect_perf_agent() {
         $evt = get_network_event();
-        $agent = $ent['agent'];
-        return preg_match('(PingdomPageSpeed|GTmetrix)', $agent) === 1);
+        $agent = $evt['agent'];
+        return preg_match('(PingdomPageSpeed|GTmetrix)', $agent) === 1;
     }
 }