diff --git a/core/modules/simpletest/src/TestFileCreationTrait.php b/core/modules/simpletest/src/TestFileCreationTrait.php
index 2341432..8be0737 100644
--- a/core/modules/simpletest/src/TestFileCreationTrait.php
+++ b/core/modules/simpletest/src/TestFileCreationTrait.php
@@ -12,11 +12,11 @@
 trait TestFileCreationTrait {
 
   /**
-   * Whether or not the test files have been generated.
+   * Whether the files were copied to the test files directory.
    *
    * @var bool
    */
-  protected $generatedTestFiles;
+  protected $generatedTestFiles = FALSE;
 
   /**
    * Gets a list of files that can be used in tests.
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 89994e1..2862751 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -170,11 +170,6 @@
   protected $sessionId = NULL;
 
   /**
-   * Whether the files were copied to the test files directory.
-   */
-  protected $generatedTestFiles = FALSE;
-
-  /**
    * The maximum number of redirects to follow when handling responses.
    */
   protected $maximumRedirects = 5;