Except when the parties otherwise expressly agree in writing, a borrower of money must pay the amount due in such money as is current at the time when the loan becomes due, whether such money is worth more or less than the actual money lent.
Okla. Stat. tit. 15, § 262
Repayment must be made in current funds
R.L. 1910, § 1000
Official source: Oklahoma Legislature. Reproduced from public-domain Oklahoma statutes; confirm against the official source for the current text. Not legal advice.