These are dark times for the people of Puerto Rico. Their island is over $70 billion in debt. Unemployment and misery is rampant, amid crushing austerity to pay off their growing obligations. Puerto Rico’s peculiar structure as a territory — not a U.S. state, not an independent country — makes it nearly impossible for it to crawl its way out of this hole. One possible safety valve, a Supreme Court case that would have allowed Puerto Rico to restructure its debt, was rejected.

That leaves Congress’ solution: a bill called PROMESA that allows an unelected fiscal oversight board with no ties to Puerto Rico to effectively colonize the commonwealth, taking what’s left of its sovereignty and dictating the island’s political and economic future.

Related: Is Your State the Next Puerto Rico?

PROMESA, which allows the oversight board to order a debt-restructuring process after exhausting options containing even more austerity (including cutting worker protections like the minimum wage and privatizing infrastructure projects), already passed the House. Next week the Senate will take it up. Because of a July 1 deadline for Puerto Rico to make $2 billion in bond payments, and the fact that the House has adjourned and cannot change the bill it passed, leaders will likely pressure for PROMESA’s quick passage with no changes.

But there’s a problem. A group of Puerto Rican credit unions has opposed PROMESA, highlighting a quirk in the bill that would devastate one of the largest sources of credit on the island. Not only would PROMESA mean the loss of self-governance and more punishing austerity, it could wipe out the Puerto Rican banking system as we know it.

Puerto Ricans use credit unions in high numbers. A letter to Senate Energy and Natural Resources Committee Chair and PROMESA bill sponsor Lisa Murkowski from Sosa Lloréns Cruz Neris, a Puerto Rican law firm, claims that 1.2 million people have either deposits or loans with credit unions, representing over one in three residents. State-chartered credit unions hold $8.47 billion in assets.

Related: What You Need to Know About Puerto Rico’s Ongoing Debt Crisis

By local law, these state-chartered credit unions must hold Puerto Rican debt as part of their regulatory capital. In fact, the government demanded that credit unions increase their holdings in Puerto Rican bonds in 2009, limiting other options for their capital. So if a post-PROMESA debt restructuring forces haircuts equally on all creditors, that will wither the capital for these credit unions, putting many at risk of insolvency.

That doesn’t mean that 1.2 million depositors would lose their money; Puerto Rican credit unions are protected by a deposit insurance system. But it does mean that the collapse would freeze local lending, precisely the outcome PROMESA purports to prevent, if the goal is to rescue the island’s economy. That includes personal loans, and the majority of Puerto Rico’s credit union customers are low- to middle-income families and senior citizens. The island’s economy is already in bad enough shape. According to the credit unions, PROMESA would not only stunt it further, but also put the burden on the most vulnerable members of society.

There’s a way to prevent this while still giving Puerto Rico debt relief. The credit unions endorsed the plan of a separate bill, put forward by Vermont senator and presidential candidate Bernie Sanders. The Sanders plan sets up a third-party corporation to purchase Puerto Rican debt, becoming the sole creditor for the island, able to rework terms for a resolution. But there’s one unique feature to the proposal: The third-party corporation only pays out the price of the bond paid for by each creditor.

Many so-called “vulture funds” scooped up Puerto Rican debt in the secondary market at fire sale prices. They sought a quick payday by buying in low and seeking to force full repayment of the face value of the bonds. The Sanders bill refuses to reward this profit-making scheme, paying back only what was paid in the first place. So vulture funds that paid 20 cents on every dollar of face value for bonds would only get 20 cents on the dollar back.

Related: Why Hedge Funds May Not Get a Windfall from Puerto Rico

This would also protect primary market investors, like mutual funds and the credit unions, who bought Puerto Rican debt at its face value years ago. They would not suffer in the same way that they would with a blanket haircut imposed by PROMESA’s oversight board. Instead of rewarding vulture funds for their opportunism and hurting traditional investors — including Puerto Rican citizens — the Sanders approach would allocate available funds more equitably.

Sosa Lloréns Cruz Neris calls this the “Entry Point” solution, and they argue that through this approach, “the goals of an effective debt restructuring can be achieved, treating investors fairly and without hurting Puerto Rico’s economy.” Since vulture funds have re-run this strategy around the world, from Argentina to Greece to Detroit, and would surely target more U.S. municipalities if they got the chance, instituting the Entry Point principle would “prevent instances of unjust enrichment in the context of public distress,” Sosa Lloréns Cruz Neris concludes.

Sanders could offer an amendment to PROMESA next week mandating the Entry Point feature. But with the aforementioned deadline, Republicans would be inclined to defeat anything that doesn’t speed a bill to the president’s desk. Democrats, and President Obama, must ask themselves if they’re ready to reward speculators and destroy a pillar of the Puerto Rican financial system, just so they can say they did “something” for the commonwealth.

Related: Bernie Sanders on Puerto Rico: ‘A’ for Effort; ‘D-‘ on Substance

Interestingly, this question of how to treat speculative creditors dates all the way back to the American Revolution. Alexander Hamilton and James Madison squabbled over this, in the context of paying off bonds used to finance the war effort. Hamilton wanted to pay off the creditors at face value; Madison wanted to pay them at only the rate the creditors paid, so as not to reward speculators. Hamilton eventually won out.

Lin-Manuel Miranda of Hamilton fame, who has Puerto Rican parents, has pleaded with Congress for relief for the island. He has called PROMESA “the only option that Congress is currently willing to pass,” and supported it as the least-worst solution. Hamilton would be proud of his protégé’s support for rewarding financiers for taking advantage of a government in trouble. But if Miranda looked closer at what this bill would mean for friends and family suffering on the island, maybe he wouldn’t endorse something so, well, Hamiltonian.