Thanks, everybody! Lots of useful advice there. Based on one of Murray's suggestions I'm doing this: # app/views/articles/show.html.haml :markdown #{assetify @article.content} # articles helper def assetify(text) text.gsub(%r{(/images/news/([-a-zA-Z.]*))}) { |name| asset_path("news/#{$2}") } end It does the job. Cheers, Andy