*806MERITS
Hoyt questions the sufficiency of the evidence to establish a contract provision requiring a sale of the property at Haugland’s option. The trial court found at finding I C that there was, in fact, such a contract. Our review of findings of fact is made pursuant to Rule 52(a), NDRCivP.
“A finding is ‘clearly erroneous’ only when, although there is some evidence to support it, the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been made.” In re Estate of Elmer, 210 N.W.2d 815, 820 (N.D.1973).
In this case there is substantial evidence which supports the trial court’s finding. All parties to the option agreement were involved in its negotiation. It is not, therefore, a “contract of adhesion”1 and we do not construe all ambiguities against Haugland, even though his attorney acted as the scrivener. The contract here was the product of arm’s-length negotiation. At trial, Duwayne Hoyt acknowledged that he understood the import and effect of the option contract. The finding that Hoyt contracted to sell the land at Haugland’s option is supported by evidence and is not clearly erroneous.
Hoyt next contends that the option was not properly exercised and is, therefore, void and of no effect. He contends that the acceptance was not proper because the cashier’s check was made payable to the Hoyts and to a third party, Federal Land Bank. It is argued that this method of tender added a new term and was thus only a qualified acceptance. Ordinarily, an option will not be enforced until it is accepted by the optionee, within the time and upon the terms and conditions provided in the option. Alfson v. Anderson, 78 N.W.2d 693 (N.D.1956); Horgan v. Russell, 24 N.D. 490, 140 N.W. 99 (1913). We therefore look to the terms of the option contract to determine if the acceptance complies with those terms. The contract states that the price of $31,717.00 is “to be paid in full at the time this option is exercised.” This term would seem to support Hoyt’s argument that tender was ineffective. However, it is un-denied that (1) the Federal Land Bank was named as a payee because Hoyt had mortgaged the property to the bank; (2) a letter notified Hoyt of the availability of the cashier’s check; and (3) Hoyt made no response whatsoever to Haugland’s numerous indications of his intentions to exercise the option. It is additionally noted that Hoyt was only entitled to the $31,717.00 upon his furnishing an “abstract of title showing good and merchantable title free from all spread taxes, special assessments, liens and encumbrances . . . . ” It is undenied that no such abstract was furnished or could be furnished without a release from the Federal Land Bank. Additionally, Hoyt’s testimony indicates that he did not intend to convey, pursuant to the option, for reasons arising before the cashier’s check was drawn and not relating to the additional payee name on that check.
The trial court found, as a fact, that Haugland “made a complete and proper election to purchase said property and tender of consideration . . . . ” That finding is further explained by the memorandum opinion of the trial court wherein it is stated that:
“It was a proper tender. There was no objection to the form in which the tender was made. There was no attempt to even request opposing [sic] Mr. Haugland to revise the tender showing him that the West Half of 18 would, in fact be clear of the mortgage.”
Section 9-12-18, NDCC, provides:
“The creditor must make objections to the mode of an offer of performance at the time it is made to him. If this is not done, any objection which could have been obviated at that time is waived by his failure to make the same.”
*807See, also, Kuhn v. Hamilton, 117 N.W.2d 81 (N.D.1962), and Kuhn v. Hamilton, 138 N.W.2d 604, 608 (N.D.1965); Kern v. Kelner, 77 N.D. 948, 48 N.W.2d 90, 106 (1951); Ugland v. Farmers’ & Merchants’ State Bank, 23 N.D. 536, 137 N.W. 572 (1912).
The finding of fact is supported by evidence and is not clearly erroneous. Because there was no timely objection to the tender, it became a proper tender as a matter of law.
CROSS-APPEAL
Haugland argues that finding number III, that an equitable mortgage was created by the parties’ transaction, is clearly erroneous. We agree.
Except for the option contract, the facts of this case are strikingly similar to those in Ginter v. Ginter, 63 N.W.2d 394, 396 (N.D.1954). There, this Court said:
“In considering whether a deed was executed for purposes of a sale or for purposes of security, and therefore a mortgage, the essential thing is to determine the intention of the parties at the time of the transaction.” [Citations omitted.]
In Ginter, and in the instant ease, both parties to the transaction testified that a sale took place. It is undisputed that Haugland originally sold to Hoyt because he was in danger of losing his property and had serious need of financing. Notwithstanding this, all the formalities for a sale were completed in 1972. Hoyt went into possession, as owner, in 1972. Hoyt treated the property as his own to the extent of paying taxes and mortgaging it. There is no testimony which supports a finding that an equitable mortgage, not a sale, was intended.
The trial court committed clear error in finding that an equitable mortgage was created on January 13, 1972. Because there was no equitable mortgage, it was likewise error for the trial court to conclude that interest on that mortgage, for a period of five years, in the amount of $6,343.40, was due to Hoyt from Haugland.
CONCLUSION
The motion to dismiss the appeal is denied. The judgment is reversed only insofar as it allows Hoyt interest in the amount of $6,343.40, otherwise it is affirmed. This case is remanded for judgment in conformance with the opinion.
ERICKSTAD, C. J., and PAULSON, SAND and VOGEL, JJ., concur.. See discussion of contracts of adhesion in St. ex rel. Hagen, Etc. v. Bismarck Tire Ctr., 234 N.W.2d 224, 225 (N.D.1975).