5-8.7 Correcting Mistakes A contract may be modified to correct or mitigate the effect of a mistake. Examples are the following: A mistake or ambiguity consisting of the failure to express, or express clearly, in a written contract, the agreement as both parties understood it. A supplier’s mistake so obvious that it was or should have been apparent to the CO. A mutual mistake concerning a material fact (particularly, mistakes concerning the promises the parties made to one another under the contract). A claim of mistake that is asserted after contract award, and a decision to deny a claim of mistake asserted after contract award, in whole or in part, is handled under the procedures of Clause B-9: Claims and Disputes.