In my article “The truth about geopolymers” by S. Grzeszczyk, Cement Wapno Beton, 26 (3) (2021), 101-108, there is an information I would like to rectify. There is a sentence: “Industrial application of geopolymers in Poland is limited to the activity of professor Maolepszy, who used this binder of blast furnace slag activated with NaOH addition to the construction of the students’ hotel, in Cracow.” It should be: “The activity of professor Małolepszy includes the use of a slag-alkali binder, in which the activator was sodium carbonate. This material was used for the manufacturing of precast concrete units of the” Żerań “type, of which a building was erected in the 1970s in the area of the “Prefabet” company in Kraków, Poland. This building was examined for twenty years in terms of concrete strength and durability. In practice, a total of about 100 thousand cubic meters of slag-alkali concrete has been used in Poland.”