diff --git a/mozilla/js/tests/lc3/forin/object-001.js b/mozilla/js/tests/lc3/forin/object-001.js
index 4beb9dbe3d8..78b9b2fc60f 100644
--- a/mozilla/js/tests/lc3/forin/object-001.js
+++ b/mozilla/js/tests/lc3/forin/object-001.js
@@ -120,7 +120,7 @@
         this.pCount = 0;
         for ( var p in o ) {
             this.pCount++;
-            if ( typeof p == "number" ) {
+            if (!isNaN(p)) {
                 eval( "this["+p+"] = o["+p+"]" );
             } else {
                 eval( "this." + p + " = o."+ p );