diff --git a/tests/SessionTest.php b/tests/SessionTest.php
index 1587f14..91732a3 100644
--- a/tests/SessionTest.php
+++ b/tests/SessionTest.php
@@ -52,5 +52,10 @@ final class SessionTest extends TestCase
 
         $this->assertSame(self::$session->get(self::$k1), self::$v2);
     }
+
+    public function testGetNonexistentValue(): void
+    {
+        $this->assertNull(self::$session->get('undefined'));
+    }
 }
 ?>