diff --git a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldPHIDs.php b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldPHIDs.php
--- a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldPHIDs.php
+++ b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldPHIDs.php
@@ -118,7 +118,7 @@
       $old = array();
     }
 
-    $new = phutil_json_decode($xaction->getNewValue());
+    $new = json_decode($xaction->getNewValue());
     if (!is_array($new)) {
       $new = array();
     }