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. <EOS>