diff --git a/src/Model/Item.php b/src/Model/Item.php
index 0c48c95291..3e0faddf75 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -1061,13 +1061,7 @@ class Item
 
 		// Create Diaspora signature
 		if ($item['origin'] && empty($item['diaspora_signed_text']) && ($item['gravity'] != GRAVITY_PARENT)) {
-			if ($uid == 0) {
-				$sender_contact = Contact::getById($item['contact-id'], ['uid']);
-				$sender_uid = $sender_contact['uid'];
-			} else {
-				$sender_uid = $uid;
-			}
-			$signed = Diaspora::createCommentSignature($sender_uid, $item);
+			$signed = Diaspora::createCommentSignature($item);
 			if (!empty($signed)) {
 				$item['diaspora_signed_text'] = json_encode($signed);
 			}
diff --git a/src/Protocol/Diaspora.php b/src/Protocol/Diaspora.php
index 53140521d0..2c3e9add63 100644
--- a/src/Protocol/Diaspora.php
+++ b/src/Protocol/Diaspora.php
@@ -4044,14 +4044,25 @@ class Diaspora
 	/**
 	 * Creates the signature for Comments that are created on our system
 	 *
-	 * @param integer $uid  The user of that comment
 	 * @param array   $item Item array
 	 *
 	 * @return array Signed content
 	 * @throws \Exception
 	 */
-	public static function createCommentSignature($uid, array $item)
+	public static function createCommentSignature(array $item)
 	{
+		$contact = Contact::getById($item['author-id'], ['url']);
+		if (empty($contact['url'])) {
+			Logger::warning('Author Contact not found', ['author-id' => $item['author-id']]);
+			return false;
+		}
+
+		$uid = User::getIdForURL($contact['url']);
+		if (empty($uid)) {
+			Logger::info('No owner post, so not storing signature', ['url' => $contact['url']]);
+			return false;
+		}
+
 		$owner = User::getOwnerDataById($uid);
 		if (empty($owner)) {
 			Logger::info('No owner post, so not storing signature');