diff --git a/app/models/issue.rb b/app/models/issue.rb
index 78383fc..5724ce4 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -201,6 +201,7 @@ class Issue < ActiveRecord::Base
     @workflow_rule_by_attribute = nil
     @assignable_versions = nil
     @relations = nil
+    @spent_hours = nil
     base_reload(*args)
   end