diff --git a/core/modules/block/custom_block/custom_block.pages.inc b/core/modules/block/custom_block/custom_block.pages.inc
index a1e1144..eba88fb 100644
--- a/core/modules/block/custom_block/custom_block.pages.inc
+++ b/core/modules/block/custom_block/custom_block.pages.inc
@@ -107,7 +107,7 @@ function custom_block_delete_form($form, &$form_state, CustomBlock $block) {
     );
     $form['message'] = array(
       '#type' => 'markup',
-      '#markup' => format_plural(count($instances), 'This will also remove 1 placed block instance', 'This will also remove @count placed block instances'),
+      '#markup' => format_plural(count($instances), 'This will also remove 1 placed block instance.', 'This will also remove @count placed block instances.'),
     );
   }
 
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
index 6ada3c5..baf239e 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php
@@ -131,10 +131,10 @@ public function testBlockDelete() {
 
     // Delete the block.
     $this->drupalGet('block/1/delete');
-    $this->assertText('This will also remove 1 placed block instance');
+    $this->assertText(format_plural(1, 'This will also remove 1 placed block instance.', 'This will also remove @count placed block instance.'));
 
     $this->drupalPost(NULL, array(), 'Delete');
-    $this->assertRaw(format_string('Custom block %name has been deleted.', array('%name' => $edit['info'])));
+    $this->assertRaw(t('Custom block %name has been deleted.', array('%name' => $edit['info'])));
 
     // Create another block and force the plugin cache to flush.
     $edit2 = array();