diff --git a/lib/Net/URLChecker.php b/lib/Net/URLChecker.php
index 575daac56..00ad62593 100644
--- a/lib/Net/URLChecker.php
+++ b/lib/Net/URLChecker.php
@@ -66,7 +66,7 @@ private function getHTTPResponseCode($url)
         curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
         // The PHP doc indicates that CURLOPT_CONNECTTIMEOUT_MS constant is added in cURL 7.16.2
         // available since PHP 5.2.3.
-        if (!defined(CURLOPT_CONNECTTIMEOUT_MS)) {
+        if (!defined('CURLOPT_CONNECTTIMEOUT_MS')) {
             define('CURLOPT_CONNECTTIMEOUT_MS', 156);  // default value for CURLOPT_CONNECTTIMEOUT_MS
         }
         curl_setopt($ch, CURLOPT_CONNECTTIMEOUT_MS, self::CONNECT_TIMEOUT_MS);