diff --git a/src/applications/feed/PhabricatorFeedStoryPublisher.php b/src/applications/feed/PhabricatorFeedStoryPublisher.php
index 87909af544..811160e151 100644
--- a/src/applications/feed/PhabricatorFeedStoryPublisher.php
+++ b/src/applications/feed/PhabricatorFeedStoryPublisher.php
@@ -74,7 +74,7 @@ final class PhabricatorFeedStoryPublisher {
     $story = new PhabricatorFeedStoryData();
     $story->setStoryType($this->storyType);
     $story->setStoryData($this->storyData);
-    $story->setAuthorPHID($this->storyAuthorPHID);
+    $story->setAuthorPHID((string)$this->storyAuthorPHID);
     $story->setChronologicalKey($chrono_key);
     $story->save();