Device for locking a push-button of a watchcase

A device for locking a push-button in a rest position, wherein the device comprises a push-button configured to be slidingly movably engaged in a middle between an active position and a rest position, and a control member cooperating with a blocking element so that, when the control member occupies a locking position, the blocking element immobilises the push-button in the rest position, and when the control member occupies a release position, the blocking element allows the push-button to move from its rest position, the push-button including an excrescence configured to engage, when the push-button occupies the active position, in a cavity with a complementary shape extending in the middle, the control member forcing the blocking element to close off this cavity when control member occupies the locking position, the latter being released when control member occupies the release position, the blocking element being formed by an elastic blade extending between two ends, a first of which is arranged against the control member and a second of which is configured to clear or close off the cavity depending on the position of the control member.