Broken Mower

I was going to mow the grass tomorrow, but I decided to go ahead and get it done late this afternoon. Just before I finished the front yard, the rear, right wheel fell off and the mower of course fell to the ground and scalped the grass. I was lucky enough to find the nut and washers for the bolt/axle that had fallen off, and re-attached them to finish the mowing job. But even just a few passes up and down the yard had loosened the wheel again.
Looks like I'll be going to the hardware store tomorrow and getting another wheel to install.
If it's not one thing; it's gonna be another.