diff --git a/js/cs.js b/js/cs.js
index ed8844e..4ed82e3 100644
--- a/js/cs.js
+++ b/js/cs.js
@@ -194,7 +194,7 @@ jQuery(document).ready(function($) {
 	}
 	$('#page img').each(function(){
 		alt = $(this).attr('alt')
-		if (alt){
+		if (undefined != alt){
 			alt = alt.toLowerCase()
 			//console.log('alt='+alt)	
 			if (alt.indexOf('.jpg') >= 0 || alt.indexOf('.png') >= 0 || alt.indexOf('.gif') >= 0 ){