diff --git a/app/views/repositories/_contributor.json.jbuilder b/app/views/repositories/_contributor.json.jbuilder
index da2ae37dc..dddf04398 100644
--- a/app/views/repositories/_contributor.json.jbuilder
+++ b/app/views/repositories/_contributor.json.jbuilder
@@ -6,7 +6,7 @@ if user.blank?
   json.name contributor["name"].to_s.downcase || contributor["login"].to_s.downcase
   json.email contributor["email"]
   json.image_url User::Avatar.get_letter_avatar_url(contributor["name"] || contributor["login"])
-  json.contribution_perc User.new(login: contributor["name"], mail: contributor["email"]).simple_contribution_perc(project, contributor["contribution_perc"])
+  json.contribution_perc User.new(login: (contributor["name"] || contributor["login"]), mail: contributor["email"]).simple_contribution_perc(project, contributor["contribution_perc"])
 else
   json.contributions contributor["commits"] || contributor["contributions"]
   json.id user["id"]