diff --git a/app/models/issue.rb b/app/models/issue.rb
index 4e32dce..0f0fd62 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -73,7 +73,7 @@ class Issue < ActiveRecord::Base
   validates :estimated_hours, :numericality => {:greater_than_or_equal_to => 0, :allow_nil => true, :message => :invalid}
   validates :start_date, :date => true
   validates :due_date, :date => true
-  validate :validate_issue, :validate_required_fields
+  validate :validate_issue, :validate_required_fields, :validate_subtasks
   attr_protected :id
 
   scope :visible, lambda {|*args|
@@ -757,6 +757,13 @@ class Issue < ActiveRecord::Base
     end
   end
 
+  # Validates the issue against open subtasks
+  def validate_subtasks
+    if closing? && descendants.open.any?
+      errors.add :base, I18n.t(:error_can_not_close_issue_with_open_subtasks)
+    end
+  end
+
   # Set the done_ratio using the status if that setting is set.  This will keep the done_ratios
   # even if the user turns off the setting later
   def update_done_ratio_from_issue_status
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 56a06c7..38ccbd1 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -215,6 +215,7 @@ en:
   error_ldap_bind_credentials: "Invalid LDAP Account/Password"
   error_no_tracker_allowed_for_new_issue_in_project: "The project doesn't have any trackers for which you can create an issue"
   error_no_projects_with_tracker_allowed_for_new_issue: "There are no projects with trackers for which you can create an issue"
+  error_can_not_close_issue_with_open_subtasks: "An issue with open subtasks cannot be closed"
 
   mail_subject_lost_password: "Your %{value} password"
   mail_body_lost_password: 'To change your password, click on the following link:'
diff --git a/test/unit/issue_subtasking_test.rb b/test/unit/issue_subtasking_test.rb
index 020bcfd..dc72e30 100644
--- a/test/unit/issue_subtasking_test.rb
+++ b/test/unit/issue_subtasking_test.rb
@@ -306,4 +306,25 @@ class IssueSubtaskingTest < ActiveSupport::TestCase
     parent.generate_child!(:estimated_hours => 7)
     assert_equal 12, parent.reload.total_estimated_hours
   end
+
+  def test_parent_with_open_subtasks_cannot_be_closed
+    parent = Issue.generate!
+    parent.generate_child!()
+    parent.reload
+    parent.status = IssueStatus.where(:is_closed => true).first
+    parent.save
+
+    assert_include 'An issue with open subtasks cannot be closed', parent.errors.full_messages
+  end
+
+  def test_parent_with_closed_subtasks_can_be_closed
+    parent = Issue.generate!
+    parent.generate_child!(:status => IssueStatus.where(:is_closed => true).first)
+    parent.reload
+    closed_status = IssueStatus.where(:is_closed => true).first
+    parent.status = closed_status
+
+    assert_save parent
+    assert parent.status, closed_status
+  end
 end