diff --git a/app/controllers/redmine_oauth_controller.rb b/app/controllers/redmine_oauth_controller.rb
index c743c1e..df8509c 100644
--- a/app/controllers/redmine_oauth_controller.rb
+++ b/app/controllers/redmine_oauth_controller.rb
@@ -6,8 +6,8 @@ class RedmineOauthController < AccountController
   include Helpers::MailHelper
   include Helpers::Checker
   def oauth_azure
-    if Setting.plugin_redmine_omniauth_azure[:azure_oauth_authentication]
-      session[:back_url] = params[:back_url]
+    if Setting.plugin_redmine_omniauth_azure['azure_oauth_authentication']
+      session['back_url'] = params['back_url']
       redirect_to oauth_client.auth_code.authorize_url(:redirect_uri => oauth_azure_callback_url, :scope => scopes)
     else
       password_authentication
@@ -15,11 +15,11 @@ def oauth_azure
   end
 
   def oauth_azure_callback
-    if params[:error]
-      flash[:error] = l(:notice_access_denied)
+    if params['error']
+      flash['error'] = l(:notice_access_denied)
       redirect_to signin_path
     else
-      token = oauth_client.auth_code.get_token(params[:code], :redirect_uri => oauth_azure_callback_url, :resource => "00000002-0000-0000-c000-000000000000")
+      token = oauth_client.auth_code.get_token(params['code'], :redirect_uri => oauth_azure_callback_url, :resource => "00000002-0000-0000-c000-000000000000")
       user_info = JWT.decode(token.token, nil, false)
       logger.error user_info
       
@@ -28,7 +28,7 @@ def oauth_azure_callback
       if email
         checked_try_to_login email, user_info.first
       else
-        flash[:error] = l(:notice_no_verified_email_we_could_use)
+        flash['error'] = l(:notice_no_verified_email_we_could_use)
         redirect_to signin_path
       end
     end
@@ -38,13 +38,13 @@ def checked_try_to_login(email, user)
     if allowed_domain_for?(email)
       try_to_login email, user
     else
-      flash[:error] = l(:notice_domain_not_allowed, :domain => parse_email(email)[:domain])
+      flash['error'] = l(:notice_domain_not_allowed, :domain => parse_email(email)['domain'])
       redirect_to signin_path
     end
   end
 
   def try_to_login email, info
-    params[:back_url] = session[:back_url]
+    params['back_url'] = session['back_url']
     session.delete(:back_url)
 
     user = User.joins(:email_addresses)
@@ -88,10 +88,10 @@ def try_to_login email, info
   end
 
   def oauth_client
-    @client ||= OAuth2::Client.new(settings[:client_id], settings[:client_secret],
+    @client ||= OAuth2::Client.new(settings['client_id'], settings['client_secret'],
       :site => 'https://login.windows.net',
-      :authorize_url => '/' + settings[:tenant_id] + '/oauth2/authorize',
-      :token_url => '/' + settings[:tenant_id] + '/oauth2/token')
+      :authorize_url => '/' + settings['tenant_id'] + '/oauth2/authorize',
+      :token_url => '/' + settings['tenant_id'] + '/oauth2/token')
   end
 
   def settings
diff --git a/app/views/hooks/_view_account_login_bottom.html.erb b/app/views/hooks/_view_account_login_bottom.html.erb
index 411de3a..1b83fa6 100644
--- a/app/views/hooks/_view_account_login_bottom.html.erb
+++ b/app/views/hooks/_view_account_login_bottom.html.erb
@@ -1,6 +1,6 @@
 <%= stylesheet_link_tag 'buttons', :plugin => 'redmine_omniauth_azure' %>
 
-<% if Setting.plugin_redmine_omniauth_azure[:azure_oauth_authentication] %>
+<% if Setting.plugin_redmine_omniauth_azure['azure_oauth_authentication'] %>
   <%= link_to oauth_azure_path(:back_url => back_url) do %>
     <%= button_tag :class => 'button-login' do %>
       <%= image_tag('/plugin_assets/redmine_omniauth_azure/images/azure_login_icon.png', :class => 'button-login-icon', :alt => l(:login_via_azure)) %>
diff --git a/app/views/settings/_azure_settings.html.erb b/app/views/settings/_azure_settings.html.erb
index 47afffc..ff0d635 100644
--- a/app/views/settings/_azure_settings.html.erb
+++ b/app/views/settings/_azure_settings.html.erb
@@ -1,20 +1,20 @@
 <p>
   <label>Client ID:</label>
-  <%= text_field_tag 'settings[client_id]', @settings[:client_id] %>
+  <%= text_field_tag 'settings[client_id]', @settings['client_id'] %>
 </p>
 <p>
   <label>Client Secret:</label>
-  <%= text_field_tag 'settings[client_secret]', @settings[:client_secret] %>
+  <%= text_field_tag 'settings[client_secret]', @settings['client_secret'] %>
 </p>
 <p>
   <label>Tenant ID:</label>
-  <%= text_field_tag 'settings[tenant_id]', @settings[:tenant_id] %>
+  <%= text_field_tag 'settings[tenant_id]', @settings['tenant_id'] %>
 </p>
 <p>
   <label>Available domains</label>
-  <%= text_area_tag "settings[allowed_domains]", @settings[:allowed_domains], :rows => 5 %>
+  <%= text_area_tag "settings[allowed_domains]", @settings['allowed_domains'], :rows => 5 %>
 </p>
 <p>
   <label>Oauth authentication:</label>
-  <%= check_box_tag "settings[azure_oauth_authentication]", true, @settings[:azure_oauth_authentication] %>
+  <%= check_box_tag "settings[azure_oauth_authentication]", true, @settings['azure_oauth_authentication'] %>
 </p>
diff --git a/lib/helpers/checker.rb b/lib/helpers/checker.rb
index 81fb300..f0d3fa9 100644
--- a/lib/helpers/checker.rb
+++ b/lib/helpers/checker.rb
@@ -1,11 +1,11 @@
 module Helpers
   module Checker
     def allowed_domain_for? email
-      allowed_domains = Setting.plugin_redmine_omniauth_azure[:allowed_domains]
+      allowed_domains = Setting.plugin_redmine_omniauth_azure['allowed_domains']
       return unless allowed_domains
       allowed_domains = allowed_domains.split
       return true if allowed_domains.empty?
-      allowed_domains.index(parse_email(email)[:domain])
+      allowed_domains.index(parse_email(email)['domain'])
     end
   end
 end