diff --git a/chrome/content/zotero/xpcom/translation/browser_firefox.js b/chrome/content/zotero/xpcom/translation/browser_firefox.js
index 02a9a919d..dd2986d0a 100644
--- a/chrome/content/zotero/xpcom/translation/browser_firefox.js
+++ b/chrome/content/zotero/xpcom/translation/browser_firefox.js
@@ -400,8 +400,10 @@ Zotero.Translate.IO.Read.prototype = {
 		var myIndex = Zotero.Translate.IO.maintainedInstances.indexOf(this);
 		if(myIndex !== -1) Zotero.Translate.IO.maintainedInstances.splice(myIndex, 1);
 		
-		this._rawStream.close();
-		delete this._rawStream;
+		if(this._rawStream) {
+			this._rawStream.close();
+			delete this._rawStream;
+		}
 	}
 }
 Zotero.Translate.IO.Read.prototype.__defineGetter__("contentLength",