diff --git a/core/lib/Drupal/Component/Utility/SafeMarkup.php b/core/lib/Drupal/Component/Utility/SafeMarkup.php
index 3020bbe..5dca054 100644
--- a/core/lib/Drupal/Component/Utility/SafeMarkup.php
+++ b/core/lib/Drupal/Component/Utility/SafeMarkup.php
@@ -225,6 +225,7 @@ public static function format($string, array $args) {
           break;
 
         case '!':
+        case ':':
           // Pass-through.
           if (!static::isSafe($value)) {
             $safe = FALSE;
diff --git a/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
index fae15bb..fedb8cf 100644
--- a/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/SafeMarkupTest.php
@@ -220,6 +220,8 @@ function providerFormat() {
     $tests[] = array('Placeholder text: %value', array('%value' => SafeMarkupTestSafeString::create('<span>Safe HTML</span>')), 'Placeholder text: <em class="placeholder"><span>Safe HTML</span></em>', 'SafeMarkup::format does not escape an already safe string themed as a placeholder.', TRUE);
     $tests[] = array('Verbatim text: !value', array('!value' => '<script>'), 'Verbatim text: <script>', 'SafeMarkup::format replaces verbatim string as-is.', FALSE);
     $tests[] = array('Verbatim text: !value', array('!value' => SafeMarkupTestSafeString::create('<span>Safe HTML</span>')), 'Verbatim text: <span>Safe HTML</span>', 'SafeMarkup::format replaces verbatim string as-is.', TRUE);
+    $tests[] = array('Verbatim text: :value', array(':value' => '<script>'), 'Verbatim text: <script>', 'SafeMarkup::format replaces verbatim string as-is.', FALSE);
+    $tests[] = array('Verbatim text: :value', array(':value' => SafeMarkupTestSafeString::create('<span>Safe HTML</span>')), 'Verbatim text: <span>Safe HTML</span>', 'SafeMarkup::format replaces verbatim string as-is.', TRUE);
 
     return $tests;
   }