diff --git a/app/models/issue.rb b/app/models/issue.rb
index 0101abf00..582caaa60 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1352,7 +1352,7 @@ class Issue < ActiveRecord::Base
       unless Issue.use_status_for_done_ratio? && p.status && p.status.default_done_ratio
         leaves_count = p.leaves.count
         if leaves_count > 0
-          average = p.leaves.average(:estimated_hours).to_f
+          average = p.leaves.where("estimated_hours > 0").average(:estimated_hours).to_f
           if average == 0
             average = 1
           end
diff --git a/test/unit/issue_nested_set_test.rb b/test/unit/issue_nested_set_test.rb
index 3c611be28..215cc8823 100644
--- a/test/unit/issue_nested_set_test.rb
+++ b/test/unit/issue_nested_set_test.rb
@@ -358,6 +358,18 @@ class IssueNestedSetTest < ActiveSupport::TestCase
     assert_equal 12, parent.reload.estimated_hours
   end
 
+  def test_done_ratio_of_parent_with_a_child_with_estimated_time_at_0_should_not_exceed_100
+    parent = Issue.generate!
+    Issue.generate!(:estimated_hours => 40, :parent_issue_id => parent.id)
+    Issue.generate!(:estimated_hours => 40, :parent_issue_id => parent.id)
+    Issue.generate!(:estimated_hours => 20, :parent_issue_id => parent.id)
+    Issue.generate!(:estimated_hours => 0, :parent_issue_id => parent.id)
+    parent.reload.children.each do |child|
+      child.update_attribute :status_id, 5
+    end
+    assert_equal 100, parent.reload.done_ratio
+  end
+
   def test_move_parent_updates_old_parent_attributes
     first_parent = Issue.generate!
     second_parent = Issue.generate!