In the title salt, C18H18N3O+·Cl−, the aminopyrimidine molecule is protonated at one of the pyrimidine N atoms. The chloride anion interacts with the protonated pyrimidine N—H group and one of the amino N—H groups through two N—H...Cl hydrogen bonds, forming a six-membered ring. The chloride anion interacts further with the other amino N—H group to form an additional N—H...Cl hydrogen bond, which links the molecules along [001] in a helical manner.
