diff --git a/src/.jshintrc b/src/.jshintrc
index 72a58de2e..240302db4 100644
--- a/src/.jshintrc
+++ b/src/.jshintrc
@@ -4,7 +4,6 @@
 	"newcap": false,
 	"quotmark": "double",
 	"regexdash": true,
-	"strict": true,
 	"trailing": true,
 	"undef": true,
 	"unused": true,
diff --git a/src/intro.js b/src/intro.js
index 4e7b69ec3..98815ad87 100644
--- a/src/intro.js
+++ b/src/intro.js
@@ -12,4 +12,9 @@
  * Date: @DATE
  */
 (function( window, undefined ) {
-"use strict";
+
+// Can't do this because several apps including ASP.NET trace
+// the stack via arguments.caller.callee and Firefox dies if
+// you try to trace through "use strict" call chains. (#13335)
+// Support: Firefox 18+
+//"use strict";