diff --git a/system/Session/Session.php b/system/Session/Session.php
index 5c087579a2e4..875387f29827 100644
--- a/system/Session/Session.php
+++ b/system/Session/Session.php
@@ -496,7 +496,7 @@ public function get(?string $key = null)
             return $value;
         }
 
-        if ($_SESSION === []) {
+        if (! isset($_SESSION) || $_SESSION === []) {
             return $key === null ? [] : null;
         }