diff --git a/lib/FeedItem.php b/lib/FeedItem.php
index b0095be28d5..9a435730730 100644
--- a/lib/FeedItem.php
+++ b/lib/FeedItem.php
@@ -418,6 +418,9 @@ public function setUid($uid) {
 
 		if(!is_string($uid)) {
 			Debug::log('Unique id must be a string!');
+		} elseif (preg_match('/^[a-f0-9]{40}$/', $uid)) {
+			// keep id if it already is a SHA-1 hash
+			$this->uid = $uid;
 		} else {
 			$this->uid = sha1($uid);
 		}