--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -5934,17 +5934,20 @@ class CGAbstractStaticBindingMethod(CGAb
     """
     def __init__(self, descriptor, name):
         args = [Argument('JSContext*', 'cx'), Argument('unsigned', 'argc'),
                 Argument('JS::Value*', 'vp')]
         CGAbstractStaticMethod.__init__(self, descriptor, name, "bool", args)
 
     def definition_body(self):
         unwrap = CGGeneric("""JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
-JS::Rooted<JSObject*> obj(cx, &args.callee());""")
+JS::Rooted<JSObject*> obj(cx, args.computeThis(cx).toObjectOrNull());
+if (!obj) {
+  return false;
+}""")
         return CGList([ CGIndenter(unwrap),
                         self.generate_code() ], "\n\n").define()
 
     def generate_code(self):
         assert(False) # Override me
 
 def MakeNativeName(name):
     return name[0].upper() + name[1:]