Getting EIP-155 error when deploying smart contract

Hey all. I was wondering what the best way to troubleshoot the following error when trying to deploy a smart contract on the testnet: only replay-protected (EIP-155) transactions allowed over RPC. I am using the go-ethereum package, and I am dialing in using https://rpc-mumbai.maticvigil.com. It functions correctly when I connect to a local instance of ganache.