diff --git a/src/deployer/SafeGuard.sol b/src/deployer/SafeGuard.sol
index 1d59561a5..8e534808b 100644
--- a/src/deployer/SafeGuard.sol
+++ b/src/deployer/SafeGuard.sol
@@ -273,6 +273,7 @@ contract ZeroExSettlerDeployerSafeGuard is IGuard {
     }
 
     function lockDown() external onlyOwner notLockedDown {
+        require(!safe.isOwner(address(this)));
         uint256 nonce = safe.nonce();
         bytes32 txHash = safe.getTransactionHash(
             address(this),