The light came with an alternate mount that screws on to the handlebar but it makes taking the light off more annoying, and obviously removes the ability to freely put the light on different bikes
I was hoping this design was universal but none of the straps I'm seeing online have the screw hole. Well, there is one very similar strap but I'd have to pay 13€ postage on a 5€ item which offends me on a spiritual level
You might be able to staple it. Super glue might also work.