A watch case includes a case middle made of plastic or electroformed material and a crystal. The crystal or the case middle includes elbowed catches that are each insertable in a bayonet fitting in a recess of the case middle or the crystal. The case also includes a rotation stop angularly securing the case middle and the crystal in an angular position such that a part of each catch is frontally locked behind a holding surface of the case middle or of the crystal. The rotation stop is frontally snap-fitted on the case middle and/or the crystal by snap-fit fingers that cooperate with a complementary stop surface of the case middle and/or of the crystal.