diff --git a/ethereum/contracts/common/libraries/L2ContractHelper.sol b/ethereum/contracts/common/libraries/L2ContractHelper.sol
index acc418ab8..1bcb36d3e 100644
--- a/ethereum/contracts/common/libraries/L2ContractHelper.sol
+++ b/ethereum/contracts/common/libraries/L2ContractHelper.sol
@@ -9,7 +9,7 @@ pragma solidity 0.8.20;
  */
 library L2ContractHelper {
     /// @dev The prefix used to create CREATE2 addresses.
-    bytes32 constant CREATE2_PREFIX = keccak256("zksyncCreate2");
+    bytes32 private constant CREATE2_PREFIX = keccak256("zksyncCreate2");
 
     /// @notice Validate the bytecode format and calculate its hash.
     /// @param _bytecode The bytecode to hash.
diff --git a/ethereum/contracts/zksync/libraries/Diamond.sol b/ethereum/contracts/zksync/libraries/Diamond.sol
index 5d2540851..4bc925bcc 100644
--- a/ethereum/contracts/zksync/libraries/Diamond.sol
+++ b/ethereum/contracts/zksync/libraries/Diamond.sol
@@ -14,11 +14,11 @@ library Diamond {
 
     /// @dev Magic value that should be returned by diamond cut initialize contracts.
     /// @dev Used to distinguish calls to contracts that were supposed to be used as diamond initializer from other contracts.
-    bytes32 constant DIAMOND_INIT_SUCCESS_RETURN_VALUE =
+    bytes32 internal constant DIAMOND_INIT_SUCCESS_RETURN_VALUE =
         0x33774e659306e47509050e97cb651e731180a42d458212294d30751925c551a2; // keccak256("diamond.zksync.init") - 1
 
     /// @dev Storage position of `DiamondStorage` structure.
-    bytes32 constant DIAMOND_STORAGE_POSITION = 0xc8fcad8db84d3cc18b4c41d551ea0ee66dd599cde068d998e57d5e09332c131b; // keccak256("diamond.standard.diamond.storage") - 1;
+    bytes32 private constant DIAMOND_STORAGE_POSITION = 0xc8fcad8db84d3cc18b4c41d551ea0ee66dd599cde068d998e57d5e09332c131b; // keccak256("diamond.standard.diamond.storage") - 1;
 
     event DiamondCut(FacetCut[] facetCuts, address initAddress, bytes initCalldata);
 
diff --git a/zksync/contracts/L2ContractHelper.sol b/zksync/contracts/L2ContractHelper.sol
index 2ddd038d6..21f6ca054 100644
--- a/zksync/contracts/L2ContractHelper.sol
+++ b/zksync/contracts/L2ContractHelper.sol
@@ -82,7 +82,7 @@ IEthToken constant L2_ETH_ADDRESS = IEthToken(address(SYSTEM_CONTRACTS_OFFSET +
  */
 library L2ContractHelper {
     /// @dev The prefix used to create CREATE2 addresses.
-    bytes32 constant CREATE2_PREFIX = keccak256("zksyncCreate2");
+    bytes32 private constant CREATE2_PREFIX = keccak256("zksyncCreate2");
 
     /// @notice Sends L2 -> L1 arbitrary-long message through the system contract messenger.
     /// @param _message Data to be sent to L1.
diff --git a/zksync/contracts/bridge/L2StandardERC20.sol b/zksync/contracts/bridge/L2StandardERC20.sol
index b54ef8585..a35ee8da2 100644
--- a/zksync/contracts/bridge/L2StandardERC20.sol
+++ b/zksync/contracts/bridge/L2StandardERC20.sol
@@ -22,7 +22,7 @@ contract L2StandardERC20 is ERC20PermitUpgradeable, IL2StandardToken, ERC1967Upg
         bool ignoreDecimals;
     }
 
-    ERC20Getters availableGetters;
+    ERC20Getters private availableGetters;
 
     /// @dev The decimals of the token, that are used as a value for `decimals` getter function.
     /// @notice A private variable is used only for decimals, but not for `name` and `symbol`, because standard