diff --git a/app/models/issue.rb b/app/models/issue.rb
index d3b2311..6706c27 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -195,6 +195,7 @@ class Issue < ActiveRecord::Base
     @workflow_rule_by_attribute = nil
     @assignable_versions = nil
     @relations = nil
+    @spent_hours = nil
     base_reload(*args)
   end