The present invention relates to the use of a surface-reacted calcium carbonate as anti-caking agent, wherein the surface-reacted calcium carbonate is a reaction product of natural ground or precipitated calcium carbonate with carbon dioxide and at least one acid in an aqueous medium, wherein the carbon dioxide is formed in situ by the acid treatment and/or is supplied from an external source, and to a composition comprising said anti-caking agent, as well as to a method for the production of such a composition.