Civil Code, Art. 1359

When, there having been a meeting of the minds of the parties to a contract, their true intention is not expressed in the instrument purporting to embody the agreement, by reason of mistake, fraud, inequitable conduct or accident, one of the parties may ask for the reformation of the instrument to the end that such true intention may be expressed. If mistake, fraud, inequitable conduct, or accident has prevented a meeting of the minds of the parties, the proper remedy is not reformation of the instrument but annulment of the contract.