diff --git a/src/applications/differential/customfield/DifferentialManiphestTasksField.php b/src/applications/differential/customfield/DifferentialManiphestTasksField.php
--- a/src/applications/differential/customfield/DifferentialManiphestTasksField.php
+++ b/src/applications/differential/customfield/DifferentialManiphestTasksField.php
@@ -35,7 +35,7 @@
     return $this->getFieldName();
   }
 
-  public function readValueFromRevision(DifferentialRevision $revision) {
+  protected function readValueFromRevision(DifferentialRevision $revision) {
     if (!$revision->getPHID()) {
       return array();
     }