diff --git a/lib/private/Comments/Comment.php b/lib/private/Comments/Comment.php
index c9862c64ca..7c935930f2 100644
--- a/lib/private/Comments/Comment.php
+++ b/lib/private/Comments/Comment.php
@@ -299,12 +299,12 @@ class Comment implements IComment {
 	public function setActor($actorType, $actorId) {
 		if(
 		       !is_string($actorType) || !trim($actorType)
-		    || !is_string($actorId)   || !trim($actorId)
+		    || !is_string($actorId)   || $actorId === ''
 		) {
 			throw new \InvalidArgumentException('String expected.');
 		}
 		$this->data['actorType'] = trim($actorType);
-		$this->data['actorId']   = trim($actorId);
+		$this->data['actorId']   = $actorId;
 		return $this;
 	}
 
@@ -385,7 +385,7 @@ class Comment implements IComment {
 	public function setObject($objectType, $objectId) {
 		if(
 		       !is_string($objectType) || !trim($objectType)
-		    || !is_string($objectId)   || !trim($objectId)
+		    || !is_string($objectId)   || trim($objectId) === ''
 		) {
 			throw new \InvalidArgumentException('String expected.');
 		}
diff --git a/lib/private/Comments/Manager.php b/lib/private/Comments/Manager.php
index e54218509d..024dd58b89 100644
--- a/lib/private/Comments/Manager.php
+++ b/lib/private/Comments/Manager.php
@@ -118,9 +118,9 @@ class Manager implements ICommentsManager {
 	 */
 	protected function prepareCommentForDatabaseWrite(IComment $comment) {
 		if (!$comment->getActorType()
-			|| !$comment->getActorId()
+			|| $comment->getActorId() === ''
 			|| !$comment->getObjectType()
-			|| !$comment->getObjectId()
+			|| $comment->getObjectId() === ''
 			|| !$comment->getVerb()
 		) {
 			throw new \UnexpectedValueException('Actor, Object and Verb information must be provided for saving');