diff --git a/lib/gitlab/markdown.rb b/lib/gitlab/markdown.rb
index e90de83a9b2f8ba6ccc707ccd9bfed2c6d5a79f2..bc718415f60f2e456e83f7bf09df8861c490a41d 100644
--- a/lib/gitlab/markdown.rb
+++ b/lib/gitlab/markdown.rb
@@ -231,7 +231,7 @@ module Gitlab
     end
 
     def reference_external_issue(identifier, issue_tracker, project = @project)
-      url = url_for_issue(identifier)
+      url = url_for_issue(identifier, project)
       title = issue_tracker['title']
 
       options = html_options.merge(