diff --git a/app/models/user.rb b/app/models/user.rb
index 9c8e0f02a..8b2e96afa 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -866,6 +866,10 @@ class User < Principal
     project_ids.map(&:to_i)
   end
 
+  def self.prune(age=7.days)
+    User.where("created_on < ? AND status = ?", Time.now - age, STATUS_REGISTERED).destroy_all
+  end
+
   protected
 
   def validate_password_length
diff --git a/lib/tasks/redmine.rake b/lib/tasks/redmine.rake
index c7c257bfc..574444767 100644
--- a/lib/tasks/redmine.rake
+++ b/lib/tasks/redmine.rake
@@ -40,6 +40,13 @@ namespace :redmine do
     end
   end
 
+  namespace :users do
+    desc 'Removes registered users that have not been activated after seven days.'
+    task :prune => :environment do
+      User.prune
+    end
+  end
+
   namespace :watchers do
     desc 'Removes watchers from what they can no longer view.'
     task :prune => :environment do
diff --git a/test/unit/user_test.rb b/test/unit/user_test.rb
index 32f4dd200..8b6ee5ccb 100644
--- a/test/unit/user_test.rb
+++ b/test/unit/user_test.rb
@@ -1348,4 +1348,14 @@ class UserTest < ActiveSupport::TestCase
     cv2a.reload
     assert_equal @dlopper.id.to_s, cv2a.value
   end
+
+  def test_prune_should_destroy_unactivated_old_users
+    User.generate!(:status => User::STATUS_REGISTERED, :created_on => 6.days.ago)
+    User.generate!(:status => User::STATUS_REGISTERED, :created_on => 7.day.ago)
+    User.generate!(:status => User::STATUS_REGISTERED)
+
+    assert_difference 'User.count', -2 do
+      User.prune
+    end
+  end
 end