diff --git a/admin/pages/visitors.php b/admin/pages/visitors.php
index 28efb7c5..02cd372c 100644
--- a/admin/pages/visitors.php
+++ b/admin/pages/visitors.php
@@ -36,8 +36,8 @@ $tmp = $visitors->getVisitors();
 usort($tmp, 'compare');
 
 foreach ($tmp as &$visitor) {
-	$userAgent = $visitor['user_agent'];
-	if ($userAgent == 'unknown') {
+	$userAgent = $visitor['user_agent'] ?? '';
+	if (!strlen($userAgent) || $userAgent == 'unknown') {
 		$browser = 'Unknown';
 	}
 	else {