diff --git a/lib/redmine/wiki_formatting/common_mark/fixup_auto_links_filter.rb b/lib/redmine/wiki_formatting/common_mark/fixup_auto_links_filter.rb
index 3cb81fd71..a949d8f09 100644
--- a/lib/redmine/wiki_formatting/common_mark/fixup_auto_links_filter.rb
+++ b/lib/redmine/wiki_formatting/common_mark/fixup_auto_links_filter.rb
@@ -27,8 +27,8 @@ module Redmine
       # - autolinked hi res image names that look like email addresses:
       #   <a href="mailto:printscreen@2x.png">printscreen@2x.png</a>
       class FixupAutoLinksFilter < HTML::Pipeline::Filter
-        USER_LINK_PREFIX = /(@|user:)\z/.freeze
-        HIRES_IMAGE = /.+@\dx\.(bmp|gif|jpg|jpe|jpeg|png)\z/.freeze
+        USER_LINK_PREFIX = /(@|user:)\z/
+        HIRES_IMAGE = /.+@\dx\.(bmp|gif|jpg|jpe|jpeg|png)\z/
 
         def call
           doc.search("a").each do |node|