Watch case including a case middle and a rotating bezel mounted on the upper face of the case middle, the bezel being provided with a plurality of receiving spaces regularly distributed over its lower surface, the watch case being provided with a system for locking the bezel comprising the following elements: • a first hole machined in the case middle and oriented radially with respect to the bezel, • an inner thread on at least one portion of the surface of said first hole, or on the inner surface of a tube fixedly mounted inside the first hole, • a rotating crown, the crown being secured to an arbor arranged inside the first hole, the arbor including the following elements arranged in an inward direction from the exterior of the case middle: ∘ a section provided with an external thread corresponding to said inner thread, ∘ a frustoconical section having a diameter that decreases in said direction, ∘ an end collar, • a pin arranged inside a second hole in the case middle, said second hole being oriented transversely with respect to the first hole, the pin being provided with a spring, which is prestressed in order to maintain physical contact between a first end of the pin and the external surface of the arbor, the pin being dimensioned such that its second end can be housed inside one of the receiving spaces of the bezel, and wherein the elements are arranged such that: • screwing in the crown towards the interior of the case middle causes a movement of the pin against the prestressing of the spring, through the interaction between the first end of the pin and the frustoconical section, this movement pushing the pin inside one of the receiving spaces of the bezel, and thereby locking the bezel at the end of the screwing operation, • unscrewing the crown releases the pin from said receiving space under the action of the return force exerted by the spring, and thereby unlocks the bezel at the end of the unscrewing operation. • a first hole machined in the case middle and oriented radially with respect to the bezel, • an inner thread on at least one portion of the surface of said first hole, or on the inner surface of a tube fixedly mounted inside the first hole, • a rotating crown, the crown being secured to an arbor arranged inside the first hole, the arbor including the following elements arranged in an inward direction from the exterior of the case middle: ∘ a section provided with an external thread corresponding to said inner thread, ∘ a frustoconical section having a diameter that decreases in said direction, ∘ an end collar, ∘ a section provided with an external thread corresponding to said inner thread, ∘ a frustoconical section having a diameter that decreases in said direction, ∘ an end collar, • a pin arranged inside a second hole in the case middle, said second hole being oriented transversely with respect to the first hole, the pin being provided with a spring, which is prestressed in order to maintain physical contact between a first end of the pin and the external surface of the arbor, the pin being dimensioned such that its second end can be housed inside one of the receiving spaces of the bezel, • screwing in the crown towards the interior of the case middle causes a movement of the pin against the prestressing of the spring, through the interaction between the first end of the pin and the frustoconical section, this movement pushing the pin inside one of the receiving spaces of the bezel, and thereby locking the bezel at the end of the screwing operation, • unscrewing the crown releases the pin from said receiving space under the action of the return force exerted by the spring, and thereby unlocks the bezel at the end of the unscrewing operation.