diff --git a/app/models/issue.rb b/app/models/issue.rb
index ee392b970..c6b2ab7da 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1337,7 +1337,8 @@ class Issue < ActiveRecord::Base
           if average == 0
             average = 1
           end
-          done = p.leaves.sum("COALESCE(estimated_hours, #{average}) * (CASE WHEN is_closed = #{connection.quoted_true} THEN 100 ELSE COALESCE(done_ratio, 0) END)", :joins => :status).to_f
+          done = p.leaves.sum("COALESCE(CASE WHEN estimated_hours > 0 THEN estimated_hours ELSE NULL END, #{average}) " +
+			"* (CASE WHEN is_closed = #{connection.quoted_true} THEN 100 ELSE COALESCE(done_ratio, 0) END)", :joins => :status).to_f
           progress = done / (average * leaves_count)
           p.done_ratio = progress.round
         end
diff --git a/test/unit/issue_nested_set_test.rb b/test/unit/issue_nested_set_test.rb
index 0d83671e0..3a53eb3af 100644
--- a/test/unit/issue_nested_set_test.rb
+++ b/test/unit/issue_nested_set_test.rb
@@ -302,6 +302,17 @@ class IssueNestedSetTest < ActiveSupport::TestCase
     assert_equal (50 * 20 + 20 * 10) / 30, parent.reload.done_ratio
   end
 
+  def test_parent_done_ratio_with_child_estimate_to_0_should_reach_100
+    parent = Issue.generate!
+    issue1 = Issue.generate!(:parent_issue_id => parent.id)
+    issue2 = Issue.generate!(:parent_issue_id => parent.id, :estimated_hours => 0)
+    assert_equal 0, parent.reload.done_ratio
+    issue1.reload.update_attribute :status_id, 5
+    assert_equal 50, parent.reload.done_ratio
+    issue2.reload.update_attribute :status_id, 5
+    assert_equal 100, parent.reload.done_ratio
+  end
+
   def test_parent_estimate_should_be_sum_of_leaves
     parent = Issue.generate!
     Issue.generate!(:estimated_hours => nil, :parent_issue_id => parent.id)