The present invention relates to a multi-aziridine crosslinker composition, characterized in that the composition is an aqueous dispersion having a pH ranging from 9 to 14 and comprising a multi-aziridine compound in dispersed form, wherein said multi-aziridine compound has: a. from 2 to 6 of the following structural units A: (A) whereby R1, R2, R3 and R4 are H; m is 1, R' and R'' are according to (1) or (2): (2) R'= H or an aliphatic hydrocarbon group containing from 1 to 14 carbon atoms, and R" = an alkyl group containing from 1 to 4 carbon atoms, CH2-O- (C=O)-R''' or CH2-O-R'''', whereby R''' is an alkyl group containing from 4 to 12 carbon atoms and R'''' is an alkyl group containing from 1 to 14 carbon atoms, (2) R' and R" form together a saturated cycloaliphatic hydrocarbon group containing from 5 to 8 carbon atoms; b. one or more linking chains wherein each one of these linking chains links two of the structural units A; and c. a molecular weight in the range from 600 to 10000 Daltons.