diff --git a/op/op.AddDocument.php b/op/op.AddDocument.php
index 56792736f..598d8b02a 100644
--- a/op/op.AddDocument.php
+++ b/op/op.AddDocument.php
@@ -75,7 +75,7 @@ if($user->isAdmin()) {
 	$owner = $user;
 }
 $comment  = trim($_POST["comment"]);
-$version_comment = trim($_POST["version_comment"]);
+$version_comment = !empty($_POST["version_comment"]) ? trim($_POST["version_comment"]) : '';
 if($version_comment == "" && isset($_POST["use_comment"]))
 	$version_comment = $comment;