diff --git a/contracts/MarketPlace.sol b/contracts/MarketPlace.sol
index 1a6d4a0..d2d6ac9 100644
--- a/contracts/MarketPlace.sol
+++ b/contracts/MarketPlace.sol
@@ -22,8 +22,8 @@ contract Marketplace is Ownable, HasSignature {
     address public feeToAddress;
     uint256 public transactionFee;
 
-    uint256 private constant minTransactionFee = 50;
-    uint256 private constant maxTransactionFee = 1000;
+    uint256 private constant MIN_TRANSACTION_FEE = 50;
+    uint256 private constant MAX_TRANSACTION_FEE = 1000;
 
     // Events
     event MatchTransaction(
@@ -43,7 +43,7 @@ contract Marketplace is Ownable, HasSignature {
 
     function setTransactionFee(uint256 _transactionFee) external onlyOwner {
         require(
-            _transactionFee >= minTransactionFee && _transactionFee <= maxTransactionFee,
+            _transactionFee >= MIN_TRANSACTION_FEE && _transactionFee <= MAX_TRANSACTION_FEE,
             "Marketplace: _transactionFee must >= 50 and <= 1000"
             );
         transactionFee = _transactionFee;