diff --git a/app/controllers/reservations_controller.rb b/app/controllers/reservations_controller.rb
index 17cf14640..1e3337131 100644
--- a/app/controllers/reservations_controller.rb
+++ b/app/controllers/reservations_controller.rb
@@ -37,7 +37,7 @@ def set_filter
 
     @filters = [:reserved, :checked_out, :overdue, :returned, :returned_overdue,
                 :upcoming, :requested, :approved_requests, :denied, :archived]
-    @filters << :missed unless AppConfig.first.res_exp_time
+    @filters << :missed unless AppConfig.check :res_exp_time
 
     # if filter in session set it
     if session[:filter]
diff --git a/app/mailers/user_mailer.rb b/app/mailers/user_mailer.rb
index b130a63bb..4206f1f25 100644
--- a/app/mailers/user_mailer.rb
+++ b/app/mailers/user_mailer.rb
@@ -3,10 +3,10 @@ class UserMailer < ActionMailer::Base
   # Workaround so that RSpec start-up doesn't fail.
   # TODO: Have RSpec initialize AppConfig with configuration.
   add_template_helper(ApplicationHelper)
-  if AppConfig.first.nil?
-    default from: 'no-reply@reservations.app'
-  else
+  if AppConfig.check :admin_email
     default from: AppConfig.get(:admin_email), cc: AppConfig.get(:admin_email)
+  else
+    default from: 'no-reply@reservations.app'
   end
 
   # checks the status of the current reservation and sends the appropriate email
diff --git a/config/initializers/00_devise.rb b/config/initializers/00_devise.rb
index 195ad05bf..2a7a17639 100644
--- a/config/initializers/00_devise.rb
+++ b/config/initializers/00_devise.rb
@@ -11,8 +11,9 @@
   # Configure the e-mail address which will be shown in Devise::Mailer,
   # note that it will be overwritten if you use your own mailer class
   # with default "from" parameter.
-  config.mailer_sender = if AppConfig.table_exists? && !AppConfig.first.nil?
-                           AppConfig.first.admin_email
+  config.mailer_sender = if AppConfig.table_exists? &&
+                            AppConfig.check(:admin_email)
+                           AppConfig.get :admin_email
                          else
                            'admin@reservations.app'
                          end
diff --git a/spec/controllers/contact_controller_spec.rb b/spec/controllers/contact_controller_spec.rb
index 1cf2c34c0..999e44721 100644
--- a/spec/controllers/contact_controller_spec.rb
+++ b/spec/controllers/contact_controller_spec.rb
@@ -69,7 +69,7 @@
 
     it 'sends the message to the admin address' do
       expect(ActionMailer::Base.deliveries.last.to).to\
-        include(AppConfig.first.admin_email)
+        include(AppConfig.check(:admin_email))
     end
   end
 end
diff --git a/spec/features/guest_spec.rb b/spec/features/guest_spec.rb
index 07a9c6cf8..ff50e5a82 100644
--- a/spec/features/guest_spec.rb
+++ b/spec/features/guest_spec.rb
@@ -55,7 +55,7 @@
     end
 
     it 'correctly sets the setting' do
-      expect(AppConfig.first.enable_guests).to be_truthy
+      expect(AppConfig.check(:enable_guests)).to be_truthy
     end
 
     it_behaves_like 'unauthorized'
@@ -127,7 +127,7 @@
     end
 
     it 'correctly sets the setting' do
-      expect(AppConfig.first.enable_guests).to be_falsey
+      expect(AppConfig.check(:enable_guests)).to be_falsey
     end
 
     it_behaves_like 'unauthorized'
diff --git a/spec/mailers/admin_mailer_spec.rb b/spec/mailers/admin_mailer_spec.rb
index 3f09f7d41..6a4a11331 100644
--- a/spec/mailers/admin_mailer_spec.rb
+++ b/spec/mailers/admin_mailer_spec.rb
@@ -4,7 +4,7 @@
 shared_examples_for 'a valid admin email' do
   it 'sends to the admin' do
     expect(@mail.to.size).to eq(1)
-    expect(@mail.to.first).to eq(AppConfig.first.admin_email)
+    expect(@mail.to.first).to eq(AppConfig.check(:admin_email))
   end
   it "is from no-reply@#{ActionMailer::Base.default_url_options[:host]}" do
     expect(@mail.from).to \
diff --git a/spec/mailers/user_mailer_spec.rb b/spec/mailers/user_mailer_spec.rb
index c9f38ad01..d1974bff7 100644
--- a/spec/mailers/user_mailer_spec.rb
+++ b/spec/mailers/user_mailer_spec.rb
@@ -13,7 +13,7 @@
   # FIXME: Workaround for #398 disables this functionality for RSpec testing
   # it "is from the admin" do
   #   expect(@mail.from.size).to eq(1)
-  #   expect(@mail.from.first).to eq(AppConfig.first.admin_email)
+  #   expect(@mail.from.first).to eq(AppConfig.check :admin_email)
   # end
 end