diff --git a/app/models/post.rb b/app/models/post.rb
index 17e5104fe..8858905d6 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -113,14 +113,14 @@ class Post < ActiveRecord::Base
 
     def seo_tag_string
       if Danbooru.config.enable_seo_post_urls && !CurrentUser.user.disable_tagged_filenames?
-        "--#{seo_tags}--"
+        "__#{seo_tags}__"
       else
         nil
       end
     end
 
     def seo_tags
-      @seo_tags ||= humanized_essential_tag_string.gsub(/[^a-z0-9]+/, "-").gsub(/(?:^-+)|(?:-+$)/, "").gsub(/-{2,}/, "-")
+      @seo_tags ||= humanized_essential_tag_string.gsub(/[^a-z0-9]+/, "_").gsub(/(?:^_+)|(?:_+$)/, "").gsub(/_{2,}/, "_")
     end
 
     def preview_file_url