diff --git a/app/models/user.rb b/app/models/user.rb
index 7d6ca2380..71db4ee2e 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -22,6 +22,7 @@ class User < ActiveRecord::Base
   has_many :comments, -> { with_hidden }
 
   validates :username, presence: true, unless: :organization?
+  validates :username, uniqueness: true, unless: :organization?
   validates :official_level, inclusion: {in: 0..5}
   validates_format_of :email, without: OMNIAUTH_EMAIL_REGEX, on: :update
 
diff --git a/spec/factories.rb b/spec/factories.rb
index e541c1b20..aaa9f222c 100644
--- a/spec/factories.rb
+++ b/spec/factories.rb
@@ -1,9 +1,9 @@
 FactoryGirl.define do
   factory :user do
-    username         'Manuela'
-    sequence(:email) { |n| "manuela#{n}@madrid.es" }
-    password         'judgmentday'
-    confirmed_at     { Time.now }
+    sequence(:username) { |n| "Manuela#{n}" }
+    sequence(:email)    { |n| "manuela#{n}@madrid.es" }
+    password            'judgmentday'
+    confirmed_at        { Time.now }
 
     trait :hidden do
       hidden_at Time.now
diff --git a/spec/features/comments_spec.rb b/spec/features/comments_spec.rb
index f7e62c067..e4832a263 100644
--- a/spec/features/comments_spec.rb
+++ b/spec/features/comments_spec.rb
@@ -11,7 +11,7 @@ feature 'Comments' do
 
     expect(page).to have_css('.comment', count: 3)
 
-    comment = Comment.first
+    comment = Comment.last
     within first('.comment') do
       expect(page).to have_content comment.user.name
       expect(page).to have_content time_ago_in_words(comment.created_at)
diff --git a/spec/support/common_actions.rb b/spec/support/common_actions.rb
index 1bcc971f4..e16bbac98 100644
--- a/spec/support/common_actions.rb
+++ b/spec/support/common_actions.rb
@@ -4,7 +4,7 @@ module CommonActions
     visit '/'
     click_link 'Sign up'
 
-    fill_in 'user_username',              with: 'Manuela Carmena'
+    fill_in 'user_username',              with: "Manuela Carmena #{rand(99999)}"
     fill_in 'user_email',                 with: email
     fill_in 'user_password',              with: password
     fill_in 'user_password_confirmation', with: password