diff --git a/core/modules/aggregator/src/Entity/Feed.php b/core/modules/aggregator/src/Entity/Feed.php
index a5ed081..8e68b4d 100644
--- a/core/modules/aggregator/src/Entity/Feed.php
+++ b/core/modules/aggregator/src/Entity/Feed.php
@@ -218,7 +218,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
 
     $fields['description'] = BaseFieldDefinition::create('string_long')
       ->setLabel(t('Description'))
-      ->setDescription(t("The parent website's description that comes from the !description element in the feed.", array('!description' => '<description>')));
+      ->setDescription(t("The parent website's description that comes from the @description element in the feed.", array('@description' => '<description>')));
 
     $fields['image'] = BaseFieldDefinition::create('uri')
       ->setLabel(t('Image'))
diff --git a/core/modules/aggregator/src/FeedViewBuilder.php b/core/modules/aggregator/src/FeedViewBuilder.php
index 50462af..d631790 100644
--- a/core/modules/aggregator/src/FeedViewBuilder.php
+++ b/core/modules/aggregator/src/FeedViewBuilder.php
@@ -114,7 +114,7 @@ public function buildComponents(array &$build, array $entities, array $displays,
         $build[$id]['feed_icon'] = array(
           '#theme' => 'feed_icon',
           '#url' => $entity->getUrl(),
-          '#title' => t('!title feed', array('!title' => $entity->label())),
+          '#title' => t('@title feed', array('@title' => $entity->label())),
         );
       }
 
diff --git a/core/modules/aggregator/src/Tests/AggregatorTestBase.php b/core/modules/aggregator/src/Tests/AggregatorTestBase.php
index 08c0c23..8a0d2c0 100644
--- a/core/modules/aggregator/src/Tests/AggregatorTestBase.php
+++ b/core/modules/aggregator/src/Tests/AggregatorTestBase.php
@@ -66,7 +66,7 @@ protected function setUp() {
   public function createFeed($feed_url = NULL, array $edit = array()) {
     $edit = $this->getFeedEditArray($feed_url, $edit);
     $this->drupalPostForm('aggregator/sources/add', $edit, t('Save'));
-    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), format_string('The feed !name has been added.', array('!name' => $edit['title[0][value]'])));
+    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), format_string('The feed @name has been added.', array('@name' => $edit['title[0][value]'])));
 
     $fid = db_query("SELECT fid FROM {aggregator_feed} WHERE title = :title AND url = :url", array(':title' => $edit['title[0][value]'], ':url' => $edit['url[0][value]']))->fetchField();
     $this->assertTrue(!empty($fid), 'The feed found in database.');
@@ -166,7 +166,7 @@ public function getDefaultFeedItemCount() {
   public function updateFeedItems(FeedInterface $feed, $expected_count = NULL) {
     // First, let's ensure we can get to the rss xml.
     $this->drupalGet($feed->getUrl());
-    $this->assertResponse(200, format_string('!url is reachable.', array('!url' => $feed->getUrl())));
+    $this->assertResponse(200, format_string('@url is reachable.', array('@url' => $feed->getUrl())));
 
     // Attempt to access the update link directly without an access token.
     $this->drupalGet('admin/config/services/aggregator/update/' . $feed->id());
@@ -185,7 +185,7 @@ public function updateFeedItems(FeedInterface $feed, $expected_count = NULL) {
 
     if ($expected_count !== NULL) {
       $feed->item_count = count($feed->items);
-      $this->assertEqual($expected_count, $feed->item_count, format_string('Total items in feed equal to the total items in database (!val1 != !val2)', array('!val1' => $expected_count, '!val2' => $feed->item_count)));
+      $this->assertEqual($expected_count, $feed->item_count, format_string('Total items in feed equal to the total items in database (@val1 != @val2)', array('@val1' => $expected_count, '@val2' => $feed->item_count)));
     }
   }
 
diff --git a/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php b/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
index 0e94425..ae3f22b 100644
--- a/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
+++ b/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
@@ -37,10 +37,10 @@ public function testUpdateFeedItem() {
     );
 
     $this->drupalGet($edit['url[0][value]']);
-    $this->assertResponse(array(200), format_string('URL !url is accessible', array('!url' => $edit['url[0][value]'])));
+    $this->assertResponse(array(200), format_string('URL @url is accessible', array('@url' => $edit['url[0][value]'])));
 
     $this->drupalPostForm('aggregator/sources/add', $edit, t('Save'));
-    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), format_string('The feed !name has been added.', array('!name' => $edit['title[0][value]'])));
+    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), format_string('The feed @name has been added.', array('@name' => $edit['title[0][value]'])));
 
     $fid = db_query("SELECT fid FROM {aggregator_feed} WHERE url = :url", array(':url' => $edit['url[0][value]']))->fetchField();
     $feed = Feed::load($fid);
@@ -62,7 +62,7 @@ public function testUpdateFeedItem() {
     $feed->refreshItems();
 
     $after = db_query('SELECT timestamp FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField();
-    $this->assertTrue($before === $after, format_string('Publish timestamp of feed item was not updated (!before === !after)', array('!before' => $before, '!after' => $after)));
+    $this->assertTrue($before === $after, format_string('Publish timestamp of feed item was not updated (@before === @after)', array('@before' => $before, '@after' => $after)));
 
     // Make sure updating items works even after uninstalling a module
     // that provides the selected plugins.