diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 9d608d8c7c..b303a2507c 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -4209,7 +4209,7 @@ Zotero.Item.prototype.fromJSON = function (json, options = {}) {
 	var isValidForType = {};
 	var setFields = new Set();
 	var { fields: extraFields, creators: extraCreators, extra } = Zotero.Utilities.Internal.extractExtraFields(
-		json.extra !== undefined ? json.extra : '',
+		json.extra || '',
 		this,
 		Object.keys(json)
 			// TEMP until we move creator lines to real creators