diff --git a/tests/unit/Framework/MockObject/Creation/MockBuilderTest.php b/tests/unit/Framework/MockObject/Creation/MockBuilderTest.php
index 6f990be75fe..08ff0825714 100644
--- a/tests/unit/Framework/MockObject/Creation/MockBuilderTest.php
+++ b/tests/unit/Framework/MockObject/Creation/MockBuilderTest.php
@@ -28,10 +28,10 @@ public function testCanCreateMockObjectWithSpecifiedClassName(): void
     {
         $className = 'random_' . md5((string) mt_rand());
 
-        $o = $this->getMockBuilder(InterfaceWithReturnTypeDeclaration::class)
+        $double = $this->getMockBuilder(InterfaceWithReturnTypeDeclaration::class)
             ->setMockClassName($className)
             ->getMock();
 
-        $this->assertSame($className, $o::class);
+        $this->assertSame($className, $double::class);
     }
 }