# Solidity types uint256 are never negative Low/Info · Three Sigma · Cross-chain liquidity layer 1 · 25th June, 2024 Finding 3S-Mitosis-N11 of the Mitosis security review. - Protocol: https://mitosis.org/ - Report: /reports/mitosis - Source: https://cdn.sanity.io/files/qoqld077/production/b6b3bd7bb47407d99e76abb7c6dc615c1db5018e.pdf --- ### Description BasicVault::_deposit() checks if amount is negative, which is unnecessary. ### Recommendation Replace <= by ==. ### Status Addressed in [#b13e220](https://github.com/mitosis-org/evm/pull/201/commits/b13e220f40b7131124d76c6e7c56f5356f3f3311). --- Related findings: - [Casting from int256 to uint256 won't revert if the number is negative, possibly leading to issues](https://0xsimao.com/findings/ostium-casting-int256-won-revert): Ostium