diff --git a/core/includes/batch.inc b/core/includes/batch.inc
index 9a1c7a3..905fb83 100644
--- a/core/includes/batch.inc
+++ b/core/includes/batch.inc
@@ -103,8 +103,11 @@ function _batch_do() {
   // Perform actual processing.
   list($percentage, $message, $label) = _batch_process();
 
-  // Escape unsafe $message or $label variables before they are sent
-  // to JavaScript.
+  // Escape unsafe variables before they are sent to JavaScript. Escaping on
+  // the javascript layer would be more complex, because we would need to
+  // transport the safeness of particular strings, so that safe strings aren't
+  // escaped accidentally, which would be more complex than escaping plain text
+  // strings here.
   if (!SafeMarkup::isSafe($message)) {
     $message = Html::escape($message);
   }
@@ -176,11 +179,14 @@ function _batch_progress_page() {
 
   $url = $batch['url']->toString(TRUE)->getGeneratedUrl();
 
-  // Ensure messages sent to markup are safe.
+  // Escape unsafe variables before they are sent to JavaScript. Escaping on
+  // the javascript layer would be more complex, because we would need to
+  // transport the safeness of particular strings, so that safe strings aren't
+  // escaped accidentally, which would be more complex than escaping plain text
+  // strings here.
   if (!SafeMarkup::isSafe($current_set['init_message'])) {
     $current_set['init_message'] = Html::escape($current_set['init_message']);
   }
-
   if (!SafeMarkup::isSafe($current_set['error_message'])) {
     $current_set['error_message'] = Html::escape($current_set['error_message']);
   }
@@ -335,7 +341,11 @@ function _batch_process() {
       $progress_message = $old_set['progress_message'];
     }
 
-    // Ensure the message safeness or escape for HTML usage.
+    // Escape unsafe variables before they are sent to JavaScript. Escaping on
+    // the javascript layer would be more complex, because we would need to
+    // transport the safeness of particular strings, so that safe strings aren't
+    // escaped accidentally, which would be more complex than escaping plain text
+    // strings here.
     if (!SafeMarkup::isSafe($progress_message)) {
       $progress_message = Html::escape($progress_message);
     }
diff --git a/core/includes/form.inc b/core/includes/form.inc
index b895b4e..61e3aa1 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -5,6 +5,7 @@
  * Functions for form and batch generation and processing.
  */
 
+use Drupal\Component\Utility\FormattableString;
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Component\Utility\UrlHelper;
@@ -743,7 +744,7 @@ function batch_set($batch_definition) {
 
     // Tweak init_message to avoid the bottom of the page flickering down after
     // init phase.
-    $batch_set['init_message'] = SafeMarkup::format('@message<br>&nbsp;', ['@message' => $batch_set['init_message']]);;
+    $batch_set['init_message'] = new FormattableString('@message<br>&nbsp;', ['@message' => $batch_set['init_message']]);;
 
     // The non-concurrent workflow of batch execution allows us to save
     // numberOfItems() queries by handling our own counter.