diff --git a/mozilla/webtools/tinderbox/showbuilds.cgi b/mozilla/webtools/tinderbox/showbuilds.cgi
index b860ed5dc97..cd3ad8b2408 100755
--- a/mozilla/webtools/tinderbox/showbuilds.cgi
+++ b/mozilla/webtools/tinderbox/showbuilds.cgi
@@ -624,7 +624,7 @@ sub print_javascript {
       if (noDHTML) {
         return true;
       }
-      if (document.layers) {
+      if (typeof document.layers != 'undefined') {
         var l  = document.layers['popup'];
         l.src  = d.target.href;
         l.top  = d.target.y - 6;
@@ -655,7 +655,7 @@ sub print_javascript {
         document.location = log_url(logfile);
         return false;
       }
-      if (document.layers) {
+      if (typeof document.layers != 'undefined') {
         var l = document.layers['popup'];
         l.document.write("<table border=1 cellspacing=1><tr><td>"
                          + notes[noteid] + "</tr></table>");
@@ -692,7 +692,7 @@ sub print_javascript {
         document.location = logurl;
         return false;
       }
-      if (document.layers) {
+      if (typeof document.layers != 'undefined') {
         var q = document.layers["logpopup"];
         q.top = e.target.y - 6;
 
diff --git a/mozilla/webtools/tinderbox/tinderboxen.html b/mozilla/webtools/tinderbox/tinderboxen.html
index 3383bc2aeee..d502a95217b 100644
--- a/mozilla/webtools/tinderbox/tinderboxen.html
+++ b/mozilla/webtools/tinderbox/tinderboxen.html
@@ -44,7 +44,7 @@
   }
 
 
-  if(document.layers) {
+  if (typeof document.layers != 'undefined') {
       // 4.x 
       printLayer($tree1);
       document.write("<hr>");