diff --git a/app/views/projects/_md_preview.html.haml b/app/views/projects/_md_preview.html.haml
index f356a25dbfa..b869fd6e12a 100644
--- a/app/views/projects/_md_preview.html.haml
+++ b/app/views/projects/_md_preview.html.haml
@@ -9,5 +9,5 @@
 %div
   .md-write-holder
     = yield
-  .md-preview-holder.hide
+  .md.md-preview-holder.hide
     .js-md-preview{class: (preview_class if defined?(preview_class))}