diff --git a/chrome/content/zotero/xpcom/translation/translate_firefox.js b/chrome/content/zotero/xpcom/translation/translate_firefox.js
index 4f4930573..a50a8a532 100644
--- a/chrome/content/zotero/xpcom/translation/translate_firefox.js
+++ b/chrome/content/zotero/xpcom/translation/translate_firefox.js
@@ -462,9 +462,14 @@ Zotero.Translate.SandboxManager.prototype = {
 				if(isFunction) {
 					attachTo[localKey] = function() {
 						var args = Array.prototype.slice.apply(arguments);
-						for(var i=0; i<args.length; i++) {
-							if(typeof args[i] === "object" && args[i] !== null && args[i].wrappedJSObject) {
-								args[i] = args[i].wrappedJSObject;
+						if(Zotero.platformMajorVersion >= 32) {
+							// This is necessary on Nightly and works
+							// fine on 31, but apparently ZU.xpath in
+							// an unusual way on 24
+							for(var i=0; i<args.length; i++) {
+								if(typeof args[i] === "object" && args[i] !== null && args[i].wrappedJSObject) {
+									args[i] = args[i].wrappedJSObject;
+								}
 							}
 						}
 						if(passAsFirstArgument) args.unshift(passAsFirstArgument);