diff --git a/lib/rails/html/sanitizer.rb b/lib/rails/html/sanitizer.rb
index b3712a7..ffe131d 100644
--- a/lib/rails/html/sanitizer.rb
+++ b/lib/rails/html/sanitizer.rb
@@ -106,6 +106,7 @@ module SafeList
                                            "ins",
                                            "kbd",
                                            "li",
+                                           "mark",
                                            "ol",
                                            "p",
                                            "pre",