diff --git a/app/views/layouts/header/_public.html.haml b/app/views/layouts/header/_public.html.haml
index 241b2d9d74b18b63a6f4f0932db23ed3c6925758..bc59bdbd60f352aa420664adff4138834c883c1c 100644
--- a/app/views/layouts/header/_public.html.haml
+++ b/app/views/layouts/header/_public.html.haml
@@ -9,6 +9,6 @@
 
       - unless current_controller?('sessions')
         .pull-right
-          = link_to "Sign in", user_omniauth_authorize_path(:cas), class: 'btn btn-sign-in btn-success btn-sm'
+          = link_to "Sign in", user_omniauth_authorize_path(:cas), method: :post, class: 'btn btn-sign-in btn-success btn-sm'
 
 = render 'shared/outdated_browser'