This buckle for a fixation system of a strap to a camera includes a plate and a means for attaching the plate to a strap, the plate including a first hole, a second hole and a protrusion located between the first and second holes. A button may be received in the second hole only by inserting it in the first hole and then moving it from the first hole into the second hole, and removed from the buckle only by moving it from the second hole into the first hole and then removing it from the first hole. The plate further includes a slit extending from the second hole towards an outer edge of the plate.