Unresolved reference in view when render action with locals

action in controller:

def index
  render :index, locals: { my_var: 'show me`}
end

In view:

<p><%= my_var %></p>

I get a warning `Cannot find 'my_var'`. It is ok when instead of locals I use an instance variable

@my_var

It should not show this warning when the variable is provided via locals to the view.