diff --git a/core/tests/Drupal/Tests/UnitTestCase.php b/core/tests/Drupal/Tests/UnitTestCase.php
index e14d4fb..d4bd53f 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -127,7 +127,7 @@ public function getConfigStorageStub(array $configs) {
    * @param string $machine_name
    *   The machine name of the block plugin.
    *
-   * @return \PHPUnit_Framework_MockObject_MockObject
+   * @return \Drupal\block\BlockInterface|\PHPUnit_Framework_MockObject_MockObject
    *   The mocked block.
    */
   protected function getBlockMockWithMachineName($machine_name) {