diff --git a/core/includes/install.inc b/core/includes/install.inc
index 08f6ede..23c4938 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -549,16 +549,21 @@ function drupal_verify_profile($install_state) {
 
   $requirements = array();
 
-  if (count($missing_modules)) {
-    $modules = array();
+  $count = count($missing_modules);
+  if ($count) {
+    $build = array();
+
     foreach ($missing_modules as $module) {
-      $modules[] = '<span class="admin-missing">' . Unicode::ucfirst($module) . '</span>';
+      $count--;
+      $build[] = array('#markup' => '<span class="admin-missing">' . Unicode::ucfirst($module) . '</span>', '#suffix' => $count ? ', ' : '');
     }
+
+    $modules_list = \Drupal::service('renderer')->renderPlain($build);
     $requirements['required_modules'] = array(
       'title'       => t('Required modules'),
       'value'       => t('Required modules not found.'),
       'severity'    => REQUIREMENT_ERROR,
-      'description' => t('The following modules are required but were not found. Move them into the appropriate modules subdirectory, such as <em>/modules</em>. Missing modules: !modules', array('!modules' => implode(', ', $modules))),
+      'description' => t('The following modules are required but were not found. Move them into the appropriate modules subdirectory, such as <em>/modules</em>. Missing modules: @modules', array('@modules' => $modules_list)),
     );
   }
   return $requirements;
diff --git a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
index 6b38584..3e4a2ef 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
@@ -141,10 +141,10 @@ function settingsForm(array $form, FormStateInterface $form_state) {
   public function settingsSummary() {
     $summary = array();
 
-    $summary[] = t('Date part order: !order', array('!order' => $this->getSetting('date_order')));
+    $summary[] = t('Date part order: @order', array('@order' => $this->getSetting('date_order')));
     if ($this->getFieldSetting('datetime_type') == 'datetime') {
-      $summary[] = t('Time type: !time_type', array('!time_type' => $this->getSetting('time_type')));
-      $summary[] = t('Time increments: !increment', array('!increment' => $this->getSetting('increment')));
+      $summary[] = t('Time type: @time_type', array('@time_type' => $this->getSetting('time_type')));
+      $summary[] = t('Time increments: @increment', array('@increment' => $this->getSetting('increment')));
     }
 
     return $summary;
diff --git a/core/modules/language/src/Plugin/Derivative/LanguageBlock.php b/core/modules/language/src/Plugin/Derivative/LanguageBlock.php
index 3c54c25..34313c4 100644
--- a/core/modules/language/src/Plugin/Derivative/LanguageBlock.php
+++ b/core/modules/language/src/Plugin/Derivative/LanguageBlock.php
@@ -26,7 +26,7 @@ public function getDerivativeDefinitions($base_plugin_definition) {
       $configurable_types = $language_manager->getLanguageTypes();
       foreach ($configurable_types as $type) {
         $this->derivatives[$type] = $base_plugin_definition;
-        $this->derivatives[$type]['admin_label'] = t('Language switcher (!type)', array('!type' => $info[$type]['name']));
+        $this->derivatives[$type]['admin_label'] = t('Language switcher (@type)', array('@type' => $info[$type]['name']));
       }
       // If there is just one configurable type then change the title of the
       // block.
diff --git a/core/modules/migrate/src/MigrateExecutable.php b/core/modules/migrate/src/MigrateExecutable.php
index d2762ad..8a42bc9 100644
--- a/core/modules/migrate/src/MigrateExecutable.php
+++ b/core/modules/migrate/src/MigrateExecutable.php
@@ -148,8 +148,8 @@ public function __construct(MigrationInterface $migration, MigrateMessageInterfa
             break;
           default:
             $limit = PHP_INT_MAX;
-            $this->message->display($this->t('Invalid PHP memory_limit !limit, setting to unlimited.',
-              array('!limit' => $limit)));
+            $this->message->display($this->t('Invalid PHP memory_limit @limit, setting to unlimited.',
+              array('@limit' => $limit)));
         }
       }
       $this->memoryLimit = $limit;