When transferring property, sellers sometimes insist on rights of first refusal – the chance to be first in line to repurchase the property if their buyer later decides to sell. Rights of first refusal can be obvious advantages if your financial circumstances later change. If you’re keeping adjoining land, you may wish to protect yourself against the risk of something unattractive being built next door.

But Brit Grosskopf of Texas A&M University and Alvin Roth of Harvard University have both identified a little-recognized distinction in legal drafting that can turn this apparent blessing into a curse.

One type of first-refusal right gives the former owner the ability to regain the property by matching competing bids. Rights holders only have to equal the high bid without engaging in the auction themselves. But another form of rights of first refusal (common in certain real-estate and entertainment markets) requires the right holder to accept or reject the seller’s demand before other potential buyers are offered the same deal. If the right holder refuses the price, she forfeits the chance to match other offers.

As illustration, suppose you hold the right of first refusal for a piece of property you value at $500,000. If you only have to match prior bids, you may get a bargain if the market is weak, perhaps buying back the parcel for $400,000. But supposed you have to respond before the market has been tested. If the owner demands $475,000, you may be pushed close to your limit yet feel reluctant to risk losing the property to a higher bidder. In essence, the second type of right leaves you bidding against yourself.

As this example suggests, when the right of first refusal is on the table, make sure the specific terms won’t turn around and bite you later.