diff --git a/chrome/content/zotero/xpcom/translation/translate_firefox.js b/chrome/content/zotero/xpcom/translation/translate_firefox.js
index c6a2bd192..ff4713e37 100644
--- a/chrome/content/zotero/xpcom/translation/translate_firefox.js
+++ b/chrome/content/zotero/xpcom/translation/translate_firefox.js
@@ -78,7 +78,7 @@ Zotero.Translate.SandboxManager = function(sandboxLocation) {
 		};
 	};
 	this.sandbox.XMLSerializer.__exposedProps__ = {"prototype":"r"};
-	this.sandbox.XMLSerializer.prototype = {};
+	this.sandbox.XMLSerializer.prototype = {"__exposedProps__":{"serializeToString":"r"}};
 }
 
 /**