diff --git a/contracts/ethereum/src/v1/CasimirPool.sol b/contracts/ethereum/src/v1/CasimirPool.sol
index 4b8f00ab8..933cbb3c2 100644
--- a/contracts/ethereum/src/v1/CasimirPool.sol
+++ b/contracts/ethereum/src/v1/CasimirPool.sol
@@ -33,7 +33,7 @@ contract CasimirPool is ICasimirPool, Ownable, ReentrancyGuard {
     /*********/
 
     /** Pool ID */
-    uint32 private id;
+    uint32 private immutable id;
     /** Validator public key */
     bytes private publicKey;
     /** Operator IDs */