diff --git a/Gemfile b/Gemfile
index 558b6bb..3b08784 100644
--- a/Gemfile
+++ b/Gemfile
@@ -21,6 +21,7 @@ gem "redis"
 gem "doorkeeper", "~> 5.6"
 gem "doorkeeper-jwt"
 gem "jwt"
+gem "nkf" # required for omniauth-oauth2 in Ruby 3.4
 gem "omniauth", "~> 1.9"
 gem "omniauth-ldap2"
 gem "omniauth-oauth2"
diff --git a/Gemfile.lock b/Gemfile.lock
index cb88751..ba836b4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -168,6 +168,7 @@ GEM
     net-smtp (0.5.0)
       net-protocol
     nio4r (2.7.3)
+    nkf (0.2.0)
     nokogiri (1.16.5)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
@@ -527,6 +528,7 @@ DEPENDENCIES
   net-imap
   net-pop
   net-smtp
+  nkf
   omniauth (~> 1.9)
   omniauth-ldap2
   omniauth-oauth2
diff --git a/app/helpers/current_authority_helper.rb b/app/helpers/current_authority_helper.rb
index 96cc30a..b547665 100644
--- a/app/helpers/current_authority_helper.rb
+++ b/app/helpers/current_authority_helper.rb
@@ -8,7 +8,7 @@ def current_authority
     @current_authority ||= Authority.find_by_domain(request.host)
   end
 
-  SECRET = Rails.application.secrets.secret_key_base
+  SECRET = Rails.application.secret_key_base
 
   def configure_asset_access
     session_valid = 19.years