diff --git a/src/SteamAuth.php b/src/SteamAuth.php
index c1e6c08..16821e7 100644
--- a/src/SteamAuth.php
+++ b/src/SteamAuth.php
@@ -115,7 +115,7 @@ protected function parseSteamId()
             $matches
         );
 
-        if (is_numeric($matches[1])) {
+        if (isset($matches[1]) && is_numeric($matches[1])) {
             $this->steamId = $matches[1];
             return true;
         }