An arrangement for adjusting the diameter of a gas turbine stator includes a casing having a main portion and rings bordering a vein of a gas flow and located in front of respective levels of mobile blades of a rotor, and communication passages of a gas flow under pressure. The rings are surrounded by the casing and fixed thereto by circular groups of spacers. The rings include a wall extending from the casing to one of the rings and separating two chambers. The wall includes an outside edge curved into a spacer hook and engaged between the main portion of the casing and a respective appendage curved into a casing hook associated with the spacer hook. The communication passages of the gas flow under pressure exist between the chambers. At least one of the communication passages is realized by cavities through a junction of hooks.