diff --git a/includes/db.php b/includes/db.php
index 68b8dc3..2edbb1a 100644
--- a/includes/db.php
+++ b/includes/db.php
@@ -263,6 +263,10 @@ function update_outgoing_msg_frag($msguid, $fragid, $status) {
 		return -1;
 
 	if (is_array($frag)) {
+		if ($frag['status'] == 'delivered') {
+			logging('INFO', "Message $msguid : Fragment $fragid already delivered, ignore ack with status '$status'.");
+			return True;
+		}
 		$result = $fpdo -> update('outgoing_msg_frag')
                         -> set(
                                 array (