diff --git a/classes/File.php b/classes/File.php
index 9643b78f18..46d4d5498d 100644
--- a/classes/File.php
+++ b/classes/File.php
@@ -516,6 +516,11 @@ class File extends Managed_DataObject
         return $filepath;
     }
 
+    public function getAttachmentUrl()
+    {
+        return common_local_url('attachment', array('attachment'=>$this->getID()));
+    }
+
     public function getUrl($prefer_local=true)
     {
         if ($prefer_local && !empty($this->filename)) {
diff --git a/lib/activityobject.php b/lib/activityobject.php
index 87eea13727..ca6390b725 100644
--- a/lib/activityobject.php
+++ b/lib/activityobject.php
@@ -491,7 +491,7 @@ class ActivityObject
 
             $object->type = self::mimeTypeToObjectType($file->mimetype);
             $object->id   = TagURI::mint(sprintf("file:%d", $file->id));
-            $object->link = common_local_url('attachment', array('attachment' => $file->id));
+            $object->link = $file->getAttachmentUrl();
 
             if ($file->title) {
                 $object->title = $file->title;
diff --git a/lib/attachmentlistitem.php b/lib/attachmentlistitem.php
index 6ee3c7087b..dc22c8af29 100644
--- a/lib/attachmentlistitem.php
+++ b/lib/attachmentlistitem.php
@@ -87,8 +87,8 @@ class AttachmentListItem extends Widget
 
     function linkAttr() {
         return array('class' => 'attachment',
-                     'href' => $this->attachment->getUrl(false),
-                     'id' => 'attachment-' . $this->attachment->id,
+                     'href' => $this->attachment->getAttachmentUrl(),
+                     'id' => 'attachment-' . $this->attachment->getID(),
                      'title' => $this->linkTitle());
     }