diff --git a/tests/Pipeline/PipelineTest.php b/tests/Pipeline/PipelineTest.php
index b826ca57310f..332af26b46f3 100644
--- a/tests/Pipeline/PipelineTest.php
+++ b/tests/Pipeline/PipelineTest.php
@@ -259,6 +259,7 @@ public function testPipelineConditionable()
         $this->assertSame('foo', $_SERVER['__test.pipe.one']);
         unset($_SERVER['__test.pipe.one']);
 
+        $_SERVER['__test.pipe.one'] = null;
         $result = (new Pipeline(new Container))
             ->send('foo')
             ->when(false, function (Pipeline $pipeline) {
@@ -270,6 +271,7 @@ public function testPipelineConditionable()
 
         $this->assertSame('foo', $result);
         $this->assertNull($_SERVER['__test.pipe.one']);
+        unset($_SERVER['__test.pipe.one']);
     }
 }