Four matches and one move makes one square!? A Magic Trick?!

This is one of those so-called "bar tricks", as is done with readily available material and without too much effort.

It is, however, a real brain teaser, for anyone being challenged to solve the puzzle! The test is to form a square from four matches arranged in a cross by making only one move.

This challenge seems impossible but when you discover the solution you will kick yourself! Ok, now do this trick with your most intelligent friend ...