NH₄Cl is regarded as a canonical case exhibiting peaks ("lambda-anomalies") of physical properties at the temperatures near phase transition. Such is the "lambda-anomaly" of its thermal expansion coefficient (Fig.(b), dilatometric data by Lawson, 1940). However, to this day everybody overlooked the X-ray data (Fig (a), Dinichert, 1942) clearly showing absence of any such anomaly. They revealed independent coexistence of the phases in a temperature range and almost linear dependence of their unit cell volumes a_L³ and a_H³ (both phases are cubic) from temperature.