Artikel 4:105 Adaptation of Contract

If a party is entitled to avoid the contract for mistake but the other party indicates that it is willing to perform, or actually does perform, the contract as it was understood by the party entitled to avoid it, the contract is to be treated as if it had been concluded as the that party understood it. The other party must indicate its willingness to perform, or render such performance, promptly after being informed of the manner in which the party entitled to avoid it understood the contract and before that party acts in reliance on any notice of avoidance.

After such indication or performance the right to avoid is lost and any earlier notice of avoidance is ineffective.

Where both parties have made the same mistake, the court may at the request of either party bring the contract into accordance with what might reasonably have been agreed had the mistake not occurred.