(concurring specially).
[¶ 19] The evidence in the record is conflicting. On one hand, it appears Nick made no mistake in signing the contract. His heirs were just unhappy with the bargain he made and wanted to change the contract.
[¶20] On the other hand, the findings of fact indicate Nick made a mistake in signing *801the contract. However, Nick’s mistake, if any, was caused by his negligence because he failed to read the contract.5 Mistakes caused by negligence cannot be the basis for reformation of a contract. Nilsson v. Krueger, 69 S.D. 312, 317, 9 N.W.2d 783, 786 (1943). Nick was bound by the contract and so are his heirs. Therefore, the trial court erred in granting reformation.6
. Finding of Fact #XI indicates that Farrar "did not recall [Nick] reading the lease ... and does not know if [Nick] read the lease.”
. It is not necessary in this case to determine that the findings of fact were clearly erroneous. Nick may have stated, after signing, that he entered a two-year lease. He may have previously stated he did not intend to enter into any lease for more than two years. However, the terms of the lease he signed included the ten-year option. As the majority opinion states: "Any mistake regarding the meaning of this unambiguous written agreement stemmed from Nick’s neglect of his legal duty to read and understand the clear import of the ten-year option.” In effect, we are adding a conclusion of law: That Nick's failure to read the lease constituted negligence, which precluded reformation in this case.