During October 1934, the instruction to proceed with the proposal, initially designated "P.37", was received by PZL. An express priority was placed upon performance over armament and equipment, relying upon its high speed for its defence; as such, only a single 7.7 mm machine gun was allocated to each turret position instead of the twin-guns and 20 mm dorsal cannon previously considered. On 14 April 1935, the department issued its approval of a full-scale wooden mock-up of the aircraft, authorising the construction of a pair of prototypes along with a structural test frame.