diff --git a/db/seeds/development.rb b/db/seeds/development.rb
index 87ca3629..db581f28 100644
--- a/db/seeds/development.rb
+++ b/db/seeds/development.rb
@@ -14,14 +14,14 @@ teacher = FactoryBot.create(:teacher, email: 'teacher@example.org')
 FactoryBot.create(:learner, email: 'learner@example.org')
 external_user = FactoryBot.create(:external_user)
 
+# file types
+FileType.create_factories user: admin
+
 # execution environments
 ExecutionEnvironment.create_factories user: admin
 
 # exercises
 @exercises = find_factories_by_class(Exercise).map(&:name).index_with {|factory_name| FactoryBot.create(factory_name, user: teacher) }
 
-# file types
-FileType.create_factories
-
 # submissions
 FactoryBot.create(:submission, exercise: @exercises[:fibonacci], user: external_user)
diff --git a/db/seeds/production.rb b/db/seeds/production.rb
index ce697318..12a7c507 100644
--- a/db/seeds/production.rb
+++ b/db/seeds/production.rb
@@ -13,24 +13,24 @@ passwords = ['password', 'password confirmation'].map do |attribute|
 end
 
 if passwords.uniq.length == 1
-  FactoryBot.create(:admin, email: email, name: 'Administrator', password: passwords.first)
+  admin = FactoryBot.create(:admin, email: email, name: 'Administrator', password: passwords.first)
 else
   abort('Passwords do not match!')
 end
 
+# file types
+FileType.create_factories user: admin
+
 # execution environments
-ExecutionEnvironment.create_factories
+ExecutionEnvironment.create_factories user: admin
 
 # exercises
-Exercise.create_factories
+Exercise.create_factories user: admin
 
-# file types
-FileType.create_factories
-
-# change all resources' author
-[ExecutionEnvironment, Exercise, FileType].each do |model|
-  model.update(user_id: InternalUser.first.id)
-end
-
-# delete temporary users
-InternalUser.where.not(id: InternalUser.first.id).delete_all
+say(<<~CONFIRMATION_MESSAGE)
+  Production data has been seeded successfully. As part \
+  of this setup, a test email was sent to '#{email}'. You \
+  can safely ignore this mail as your account is already \
+  confirmed. However, if you haven't received any email, \
+  you should check the server's mail settings.
+CONFIRMATION_MESSAGE
diff --git a/spec/factories/execution_environment.rb b/spec/factories/execution_environment.rb
index 5c3b50ef..7e70b077 100644
--- a/spec/factories/execution_environment.rb
+++ b/spec/factories/execution_environment.rb
@@ -5,7 +5,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-coffee:latest' }
-    association :file_type, factory: :dot_coffee
+    file_type { association :dot_coffee, user: user }
     help
     name { 'CoffeeScript' }
     network_enabled { false }
@@ -19,7 +19,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-html:latest' }
-    association :file_type, factory: :dot_html
+    file_type { association :dot_html, user: user }
     help
     name { 'HTML5' }
     network_enabled { false }
@@ -35,7 +35,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'openhpi/co_execenv_java:latest' }
-    association :file_type, factory: :dot_java
+    file_type { association :dot_java, user: user }
     help
     name { 'Java 8' }
     network_enabled { false }
@@ -51,7 +51,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-jruby:latest' }
-    association :file_type, factory: :dot_rb
+    file_type { association :dot_rb, user: user }
     help
     name { 'JRuby 1.7' }
     network_enabled { false }
@@ -67,7 +67,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-node:latest' }
-    association :file_type, factory: :dot_js
+    file_type { association :dot_js, user: user }
     help
     name { 'Node.js' }
     network_enabled { false }
@@ -81,7 +81,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'openhpi/co_execenv_python:latest' }
-    association :file_type, factory: :dot_py
+    file_type { association :dot_py, user: user }
     help
     name { 'Python 3.4' }
     network_enabled { false }
@@ -97,7 +97,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-ruby:latest' }
-    association :file_type, factory: :dot_rb
+    file_type { association :dot_rb, user: user }
     help
     name { 'Ruby 2.2' }
     network_enabled { false }
@@ -113,7 +113,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-sinatra:latest' }
-    association :file_type, factory: :dot_rb
+    file_type { association :dot_rb, user: user }
     exposed_ports { '4567' }
     help
     name { 'Sinatra' }
@@ -130,7 +130,7 @@ FactoryBot.define do
     created_by_teacher
     default_memory_limit
     docker_image { 'hklement/ubuntu-sqlite:latest' }
-    association :file_type, factory: :dot_sql
+    file_type { association :dot_sql, user: user }
     help
     name { 'SQLite' }
     network_enabled { false }
diff --git a/spec/factories/exercise.rb b/spec/factories/exercise.rb
index 07ed6243..9425c46f 100644
--- a/spec/factories/exercise.rb
+++ b/spec/factories/exercise.rb
@@ -4,7 +4,10 @@ require 'seeds_helper'
 
 def create_seed_file(exercise, path, file_attributes = {})
   file_extension = File.extname(path)
-  file_type = FactoryBot.create(file_attributes[:file_type] || :"dot_#{file_extension.delete('.')}")
+  file_type = FactoryBot.create(
+    file_attributes[:file_type] || :"dot_#{file_extension.delete('.')}",
+    user: exercise.user
+  )
   name = File.basename(path).gsub(file_extension, '')
   file_attributes.merge!(file_type: file_type, name: name, path: path.split('/')[1..-2].join('/'), role: file_attributes[:role] || 'regular_file')
   if file_type.binary?
diff --git a/spec/factories/file_type.rb b/spec/factories/file_type.rb
index 0dc823cc..922bb52b 100644
--- a/spec/factories/file_type.rb
+++ b/spec/factories/file_type.rb
@@ -205,6 +205,10 @@ FactoryBot.define do
   end
 
   trait :singleton_file_type do
-    initialize_with { FileType.where(attributes).first_or_create }
+    initialize_with do
+      FileType.where(attributes.except(:user)).first_or_create do |file_type|
+        file_type.user = user
+      end
+    end
   end
 end