diff --git a/chrome/content/zotero/xpcom/data/dataObjects.js b/chrome/content/zotero/xpcom/data/dataObjects.js
index f7f50a3a6..624e70518 100644
--- a/chrome/content/zotero/xpcom/data/dataObjects.js
+++ b/chrome/content/zotero/xpcom/data/dataObjects.js
@@ -866,7 +866,7 @@ Zotero.DataObjects.prototype.isEditable = function (obj) {
 	if (obj.objectType == 'item' && obj.isAttachment()
 		&& (obj.attachmentLinkMode == Zotero.Attachments.LINK_MODE_IMPORTED_URL ||
 			obj.attachmentLinkMode == Zotero.Attachments.LINK_MODE_IMPORTED_FILE)
-		&& !Zotero.Libraries.get(libraryID).filesEditable(libraryID)
+		&& !Zotero.Libraries.get(libraryID).filesEditable
 	) {
 		return false;
 	}