# OstiumPriceUpKeep Verifies Reports Using Native Token Instead of LINK Low/Info · Three Sigma · RWA perpetuals DEX · 19th February, 2024 Finding 3S-OS-N11 of the Ostium security review. - Protocol: https://www.ostium.com/ - Report: /reports/ostium - Source: https://cdn.sanity.io/files/qoqld077/production/a95b9c69e0f65d1d6b0e649f0d62a362358ca8ce.pdf --- ### Description The [Chainlink documentation](https://docs.chain.link/data-streams#billing) states that verifying data streams via native blockchain gas tokens and their ERC20-wrapped versions incurs a surcharge when compared to LINK payments. However, the payment for verification on [L126](https://github.com/0xOstium/smart-contracts-threeSigma/blob/869392c4c9114ad468f6c2ea7e425269faf2fe2b/src/OstiumPriceUpKeep.sol#L126) is conducted using the native token, suggesting that it would be more cost-effective for the protocol to use LINK for payments. ### Recommendation It is advised to consult the specific section within the [documentation](https://docs.chain.link/data-streams/getting-started#examine-the-code) that details the implementation of payments using LINK and follow those guidelines. ### Status Acknowledged --- Related findings: - [Throughout code base: use Solidity native errors implementation instead of string errors.](https://0xsimao.com/findings/maple-finance-iii-solidity-native-implementation-string): Maple Finance - [In StakingAssetManager::lockERC20() the resulting note is created with asset instead of zkToken](https://0xsimao.com/findings/singularity-staking-lock-erc20-resulting): Singularity