diff --git a/chrome/content/zotero/xpcom/http.js b/chrome/content/zotero/xpcom/http.js
index 3392de2f0..61521ebf0 100644
--- a/chrome/content/zotero/xpcom/http.js
+++ b/chrome/content/zotero/xpcom/http.js
@@ -252,8 +252,10 @@ Zotero.HTTP = new function() {
 				}
 				deferred.resolve(xmlhttp);
 			} else {
-				let msg = "HTTP " + method + " " + dispURL + " failed with status code " + xmlhttp.status
-					+ ":\n\n" + xmlhttp.responseText;
+				let msg = "HTTP " + method + " " + dispURL + " failed with status code " + xmlhttp.status;
+				if (xmlhttp.responseText) {
+					msg += ":\n\n" + xmlhttp.responseText;
+				}
 				Zotero.debug(msg, 1);
 				deferred.reject(new Zotero.HTTP.UnexpectedStatusException(xmlhttp, msg));
 			}