Fiberglass shower has a crack in floor

There is a crack in the floor of our fiberglass shower stall. What would be the best way to handle this? Would it be possible to mend with a flexible adhesive or sealer, or is that too simple? Of course our main concern is to prevent leakage but we're hoping it doesn't need to be something as major as replacing the shower stall. Thanks much for any advice.

(I'm new with this forum so I hope it's ok to post this here. I have also posted in another category but as I read it, it seems like this would be a more appropriate category).