diff -u b/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
--- b/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -345,6 +345,22 @@
   }
 
   /**
+   * Provides a passthrough filter for trans.
+   *
+   * @param mixed $string
+   *   The value.
+   *
+   * @return string|null
+   *   The string, XSS admin filtered if not safe.
+   */
+  public function passthrough($string) {
+    if (!SafeMarkup::isSafe($string)) {
+      $string = Xss::filterAdmin($string);
+    }
+    return $string;
+  }
+
+  /**
    * Overrides twig_escape_filter().
    *
    * Replacement function for Twig's escape filter.
@@ -371,22 +387,6 @@
   }
 
   /**
-   * Provides a passthrough filter for trans.
-   *
-   * @param mixed $string
-   *   The value.
-   *
-   * @return string|null
-   *   The string, XSS admin filtered if not safe.
-   */
-  public function passthrough($string) {
-    if (!SafeMarkup::isSafe($string)) {
-      $string = Xss::filterAdmin($string);
-    }
-    return $string;
-  }
-
-  /**
    * Overrides twig_escape_filter().
    *
    * Replacement function for Twig's escape filter.
diff -u b/core/modules/system/tests/modules/twig_extension_test/templates/twig_extension_test.filter.html.twig b/core/modules/system/tests/modules/twig_extension_test/templates/twig_extension_test.filter.html.twig
--- b/core/modules/system/tests/modules/twig_extension_test/templates/twig_extension_test.filter.html.twig
+++ b/core/modules/system/tests/modules/twig_extension_test/templates/twig_extension_test.filter.html.twig
@@ -1,10 +1,10 @@
 <div class="testfilter">
   {{ message|testfilter }}
 </div>
-<!--
- The placeholder and passthrough filters should only be used in trans tags but
- their effects need to be tested outside trans tags.
--->
+  {#
+    The placeholder and passthrough filters should only be used in trans tags
+    but their effects need to be tested outside trans tags.
+  #}
 <div>
   {{ placeholder_text|placeholder }}
 </div>
@@ -16 +16 @@
-</div>
\ No newline at end of file
+</div>
diff -u b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
--- b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
+++ b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
@@ -54,7 +54,11 @@
 </div>
 <div>
   {% trans %}
-    {# Note this should never be necessary: we can just print the safe string in the template directly. #}
+    {#
+      Just for illustration purposes we pass in a safe string that won't be
+      filtered. This should never be necessary as instead, we could just print
+      the safe string in the template directly.
+    #}
     Safe: {{ safe_string|passthrough }}
   {% endtrans %}
 </div>