diff --git a/chrome/content/zotero/tools/testTranslators/translatorTester.js b/chrome/content/zotero/tools/testTranslators/translatorTester.js
index be87824b67..c2446e27a1 100644
--- a/chrome/content/zotero/tools/testTranslators/translatorTester.js
+++ b/chrome/content/zotero/tools/testTranslators/translatorTester.js
@@ -106,6 +106,9 @@ Zotero_TranslatorTesters = new function() {
 		};
 		
 		var runNextTester = function() {
+			if (!testers.length) {
+				return;
+			}
 			testersRunning++;
 			Zotero.debug("Testing "+testers[0].translator.label);
 			testers.shift().runTests(testerDoneCallback);