Cant hear the indicators....

So, not a problem round town, self cancelling works fine and I can hear, but at highway speeds I'll indicate to change lanes and sometimes forget to cancel. Passenger says 'Your still indicating'  and on a bright sunny day the dash indicator lights aren'so bright. Is there a simple fix ?, like a relay that clicks louder or even has an audible tone like when you get out of the car and the key's in the ignition or the you haven't put your vseat belt on.