diff --git a/core/modules/block/src/BlockInterface.php b/core/modules/block/src/BlockInterface.php
index 499ba124bf..0bcfe9ccb9 100644
--- a/core/modules/block/src/BlockInterface.php
+++ b/core/modules/block/src/BlockInterface.php
@@ -129,7 +129,7 @@ public function createDuplicateBlock($new_id = NULL, $new_theme = NULL);
    *   An array of operation links. Keys in this array will overwrite keys of
    *   operations defined in
    *   \Drupal\block\BlockListBuilder::getDefaultOperations().
-   *   Each operation link is itself an array with the following keys
+   *   Each operation link is itself an array with the following keys:
    *     - title: The title the link should display.
    *     - url: The \Drupal\Core\Url object for the link.
    *     - weight: The link weight.