diff --git a/core/tests/Drupal/Tests/Core/Config/ConfigTest.php b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
index 49869d9..827259e 100644
--- a/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
@@ -217,20 +217,6 @@ public function testSetValidation() {
   }
 
   /**
-   * Checks that a single value cannot be overwritten with a nested value.
-   *
-   * @covers ::set
-   * @expectedException PHPUnit_Framework_Error_Warning
-   */
-  public function testSetIllegalOffsetValue() {
-    // Set a single value.
-    $this->config->set('testData', 1);
-
-    // Attempt to treat the single value as a nested item.
-    $this->config->set('testData.illegalOffset', 1);
-  }
-
-  /**
    * Checks that config can be initialized with data.
    *
    * @covers ::initWithData