diff --git a/model/BlogPost.php b/model/BlogPost.php
index bed684f..3328324 100755
--- a/model/BlogPost.php
+++ b/model/BlogPost.php
@@ -110,9 +110,9 @@ class BlogPost extends Page {
 	 * Update the PublishDate to now, if being published for the first time, and the date hasn't been set to the future.
 	**/
 	public function onBeforePublish() {
-		if ($this->owner->obj('PublishDate')->InPast() && !$this->owner->isPublished()) {
-			$this->owner->setCastedField("PublishDate", time());
-			$this->owner->write();
+		if ($this->dbObject('PublishDate')->InPast() && !$this->isPublished()) {
+			$this->setCastedField("PublishDate", time());
+			$this->write();
 		}
 	}