Spanish port workers said on Thursday they would go on strike for three days this week to protest against the reform of operations aimed at liberalizing hiring practices in a heavily unionized sector.

The strike action is set for next Monday, Wednesday and Friday.

Earlier this month, Spain’s parliament passed the long-delayed reform to bring port regulation closer to that of the European Union after months of fines by the EU for failing to crack down on closed-shop hiring.

Companies currently have no say over hiring and firing at Spanish ports. The new law aims to permit them to choose their own staff rather than being bound by union-approved lists.