diff --git a/chrome/content/zotero/xpcom/translation/translate.js b/chrome/content/zotero/xpcom/translation/translate.js
index 38d8a0a5b..0c1e893eb 100644
--- a/chrome/content/zotero/xpcom/translation/translate.js
+++ b/chrome/content/zotero/xpcom/translation/translate.js
@@ -1022,6 +1022,7 @@ Zotero.Translate.Import.prototype.Sandbox = Zotero.Translate.Sandbox._inheritFro
  */
 Zotero.Translate.Import.prototype.setString = function(string) {
 	this._string = string;
+	this._io = false;
 }
 
 /**