diff --git a/src/components/script/dom/bindings/callback.rs b/src/components/script/dom/bindings/callback.rs
index 865bd9d3ef7..e267a5af709 100644
--- a/src/components/script/dom/bindings/callback.rs
+++ b/src/components/script/dom/bindings/callback.rs
@@ -85,6 +85,7 @@ impl CallbackInterface {
 
             if !callable.is_object() ||
                JS_ObjectIsCallable(cx, callable.to_object()) == 0 {
+                // FIXME(#347)
                 //ThrowErrorMessage(cx, MSG_NOT_CALLABLE, description.get());
                 return Err(());
             }
diff --git a/src/components/script/dom/bindings/utils.rs b/src/components/script/dom/bindings/utils.rs
index 36f68a93f3e..4c9c0a0b434 100644
--- a/src/components/script/dom/bindings/utils.rs
+++ b/src/components/script/dom/bindings/utils.rs
@@ -354,7 +354,7 @@ fn CreateInterfacePrototypeObject(cx: *mut JSContext, global: *mut JSObject,
 }
 
 pub extern fn ThrowingConstructor(_cx: *mut JSContext, _argc: c_uint, _vp: *mut JSVal) -> JSBool {
-    //XXX should trigger exception here
+    // FIXME(#347) should trigger exception here
     return 0;
 }