Bussola Womens Lulu Black Boot - 39

Runs quite small. 39 felt like a 38, so I exchanged it for a size 40 to have room for socks. The foot bed on the 40 seemed only a tiny bit bigger but the calf opening was unexpectedly a lot wider.The boot is very comfortable and cute, the material is very soft. I'm keeping them, but I wonder if they'll become annoying when they don't stay up.