diff --git a/app/views/layouts/header/_public.html.haml b/app/views/layouts/header/_public.html.haml
index 6a3b919ea7a362af79221d89ec25accc61033e92..5b0fbce1c9aad2b5307def0c1802db1d185ebb4c 100644
--- a/app/views/layouts/header/_public.html.haml
+++ b/app/views/layouts/header/_public.html.haml
@@ -3,7 +3,7 @@
     .header-content
       - unless current_controller?('sessions')
         .pull-right
-          = link_to "Sign in", user_omniauth_authorize_path(:cas), class: 'btn btn-sign-in btn-success'
+          = link_to "Sign in", user_omniauth_authorize_path(:cas), method: :post, class: 'btn btn-sign-in btn-success'
 
       %h1.title= title