The defendant’s first assignment of error is to the failure of the court to grant his motion for a directed verdict. He contends this should have been done because all the evidence showed that time was of the essence of the contract; that both parties intended that the sale be consummated quickly which accounted for the reduced purchase price; that neither of them foresaw the decision in Turner v. Blackburn, supra, and when the decision in that case made it impossible to consummate the sale quickly, this voided the contract. The difficulty with this argument is that the terms of the contract are not ambiguous. The contract of sale provides that the sale is to be closed within 45 days unless there is an objection to the title in which case the sale will be closed when the objection is removed. Parol evidence cannot vary these unambiguous terms. See Development Corp. v. Alderman-250 Corp., 30 N.C. App. 598, 228 S.E. 2d 72 (1976). In this case, under the terms of the contract of sale, when Turner v. Blackburn, supra, made the property unmarketable, the defendant had the choice of either expending the necessary sum to clear the title or waiting for the title to be cleared by G.S. 45-21.45 and then tendering a deed to plaintiff. He chose not to do either and conveyed the property to a third party. By doing this, he breached his contract. The defendant’s first assignment of error is overruled.
 Defendant’s second assignment of error deals with the court’s failure to charge the jury as to the doctrine of frustration. We have found few cases in this jurisdiction involving frustration. See Sechrest v. Furniture Co., 264 N.C. 216, 141 S.E. 2d 292 (1965); Sale v. Highway Commission, 242 N.C. 612, 89 S.E. 2d 290 (1955). A note in regard to frustration is found at 84 A.L.R. 2d 70 (1962) et seq. Frustration is not impossibility of performance. In England, it has been said that frustration is such a fundamental change in conditions after the contract was executed, which change occurs without fault of either party, that if performance *794were had, it would be a different thing than that for which the parties contracted. The Restatement of Contracts, § 288 provides:
Where the assumed possibility of a desired object or effect to be attained by either party to a contract forms the basis on which both parties enter into it, and this object or effect is or surely will be frustrated, a promisor who is without fault in causing the frustration, and who is harmed thereby, is discharged from the duty of performing his promise unless a contrary intention appears.
In the case sub judice, the defendant was required by the contract to tender a deed sufficient to convey a good title to the plaintiff. There was no evidence this was impossible to perform. If the defendant had delivered such a deed to the plaintiff, it would not be a different thing than that contracted for by the parties nor would the desired thing for which the parties contracted be frustrated. Difficulty of performance does not make the doctrine of frustration applicable. The defendant’s second assignment of error is overruled.
 By his third assignment of error, the defendant contends the court erred in not instructing the jury that if he could not have cleared the title within a reasonable time that he had the right to void the contract of sale. The contract provided that if the title was not cleared within a reasonable time, the buyer had the right to declare the contract null and void. The defendant, relying on 17A C.J.S. Contracts § 399 (1963) and Distributing Corp. v. Parts, Inc., 7 N.C. App. 483, 173 S.E. 2d 41 (1970), contends that if the buyer had this option under the contract, the seller had the same right. We hold the defendant was not entitled to this charge in the case sub judice. There is no evidence the defendant attempted to clear the title to the lot. Indeed the only evidence is that the defendant notified the plaintiff that if he would not take the lot as it was, the defendant would convey it to a third party.
The defendant’s last assignment of error is to the failure of the court to charge the jury that an offer by defendant to convey the lot to plaintiff with the encumberance on it was a sufficient tender under the contract. He argues that the mortgagor would have had to pay $7,500.00 to redeem the property, and the plaintiff could not have been damaged by accepting the deed. We hold that the plaintiff had the right under the contract for the defend*795ant to tender to him a deed free from any encumbrances. Anything less than this was not the performance which the contract required.
Judges Arnold and Wells concur.