diff --git a/src/lab/exp2/quizconfig.js b/src/lab/exp2/quizconfig.js
index 2bbdb114..7a50b3dc 100644
--- a/src/lab/exp2/quizconfig.js
+++ b/src/lab/exp2/quizconfig.js
@@ -28,7 +28,7 @@ for (q=1;q<=totalquestions;q++){
 		actualchoices[q]=thequestion[c].value
 		}
 		
-	if (actualchoices[q]!=correctchoices[q]){ //process an incorrect choice
+	if (actualchoices[q]!=correctchoices[q] && typeof actualchoices[q]!=='undefined'){ //process an incorrect choice
 		if (incorrect==null)
 		incorrect=q
 		else