Error reading PrivValidator state

[vldtr]

I create chain-id_priv_validator_state.json:
echo '{"height": "361402", "round": "0", "step": 3}' | jq '.' > /user/.horcrux/my-testnet/state/chain-id_priv_validator_state.json

Start horcrux:
horcrux signer start --home /user/.horcrux/my-testnet --accept-risk

And I keep getting this error:
Error reading PrivValidator state from /user/.horcrux/my-testnet/state/chain-id_priv_validator_state.json: json: cannot unmarshal string into Go value of type int32

While experimenting, I found that if I remove the quotes around the value of round (like "round": 0 instead of "round": "0"), the error disappears. But migrating.md emphasizes that quotes are needed there. Has something changed in 2.1.1?