diff --git a/chrome/content/zotero/xpcom/csl.js b/chrome/content/zotero/xpcom/csl.js
index 2267ddfb9..ddde19d21 100644
--- a/chrome/content/zotero/xpcom/csl.js
+++ b/chrome/content/zotero/xpcom/csl.js
@@ -986,7 +986,7 @@ Zotero.CSL.prototype._processElements = function(item, element, formattedString,
 								} else if(part == "day") {
 									string = string.toString();
 									if(newForm == "numeric-leading-zeros"
-											&& string.length() == 1) {
+											&& string.length == 1) {
 										string = "0" + string;
 									} else if (newForm == "ordinal") {
 										var ind = parseInt(string);