I had recently bought a nearly identical style of Bernie Mev shoes in a store; so for this purchase, I ordered the same size (40).  They were very small and narrow.  I will say; however, that my pair of Bernie Mev's that fits properly, is just about the most comfortable shoe I own.  They do expand a bit with wear.  It might be best to try this brand on before purchasing (unless you don't mind the trial and error risk of online shoe shopping).