HILL, Judge.

Plaintiffs first contend the trial court erred by excluding evidence that they received no consideration from defendant for the conveyance of the parcel of land. We do not agree.

It is well settled that except in cases of fraud, mistake, or undue influence, parol trusts or agreements will not be set up or engrafted in favor of the grantor upon a written deed conveying *797 to the grantee the absolute title, and giving clear indication on its face that such title was intended to pass. Conner v. Ridley, 248 N.C. 714, 716, 104 S.E. 2d 845 (1958). Testimony tending to show an oral agreement in direct conflict with the deed is incompetent. Conner, supra, at p. 715.

The deed was prepared by plaintiffs’ attorney (now deceased). Plaintiff M. H. Rourk testified that he had complete faith in his attorney; that he did not read the deed and did not have time to read deeds, busy as he was, all alone in the county practicing medicine. Rourk simply asked his attorney if it was all right to sign the deed. Plaintiffs only learned of the omission of a reverter clause years later when the county began to use the property as a center for the aged.

It must be assumed the plaintiffs signed the instrument they intended to sign. Poston v. Bowen, 228 N.C. 202, 203, 44 S.E. 2d 881 (1947). There is no evidence or proof of mental incapacity, mutual mistake of the parties, undue influence, or fraud. Hence, we must conclude the court did not err in refusing to allow parol evidence to contradict or modify the terms of the deed, or create a reservation of the property by parol. Campbell v. Sigmon, 170 N.C. 348, 87 S.E. 116 (1915); Conner v. Ridley, supra, at p. 716.

Next, plaintiffs contend the court erred in its findings of fact and conclusions of law that valuable consideration existed for the deed. Plaintiffs contend the language in the deed hereinafter set out simply created a condition subsequent.

TO HAVE And TO Hold THE aforesaid tract or parcel of land, . . . subject to the condition, however, that it is agreed and understood by and between the parties to this deed and made a part of the. consideration hereof that the parties of the first part are conveying the property described herein to the party of the second part upon the condition that the party of the second part shall construct on said premises a public health center . . . and that the actual construction of said health center shall commence within one year from the date of this instrument and if the construction of the said health center has not been commenced within the period of one year from the date of this instrument said property shall revert to the parties of the first part.

*798 It will be noted that the word “considertion” is used and is coupled with acts to be performed by the defendant as a part thereof. These acts so imposed clearly are a part of the consideration for the deed in that defendant normally would be under no duty to perform them. Common sense also teaches that a physician must gain some advantage in having a health center in the community.

We do not quarrel with the plaintiffs’ contention that the language creates a condition subsequent, but we have found no cases which provide that the language may not serve both to state consideration as well as to create a condition subsequent.

Plaintiffs contend the deed should be reformed on the basis of mistake. We do not agree with plaintiffs. Defendants contend the deed states exactly what they meant for it to state. Certainly, there was no mutual mistake. As a general rule, a court will allow reformation of a written instrument on the basis of mistake when the mistake is mutual and fails to express the true intent of the parties. Cobb v. Cobb, 211 N.C. 146, 189 S.E. 479 (1937); American Potato Co. v. Jeannette, 174 N.C. 236, 93 S.E. 795 (1917); Parker v. Pittman, 18 N.C. App. 500, 197 S.E. 2d 570 (1973). We have concluded previously the deed was based on consideration and not a deed of gift. Therefore, there is no basis for reformation based on unilateral mistake under Nelson v. Harris, 32 N.C. App. 375, 232 S.E. 2d 298 (1977), disc. rev. denied 292 N.C. 641 (1977).

Finally, we are not impressed by plaintiffs’ argument that the deed must be reformed on the basis of an alleged mistake by the draftsman. We note the trial judge in his findings of fact found that insufficient evidence of a mistake by the draftsman had been presented. We have searched the record and reach the same result. We are bound by the findings of fact reached by the trial judge.

The judgment reached by the trial judge is

Affirmed.

Judges MARTIN (Robert M.) and WEBB concur.