diff --git a/code/celo101-code-chapter_2/2-7-transactions-and-erc20-interface/marketplace.sol b/code/celo101-code-chapter_2/2-7-transactions-and-erc20-interface/marketplace.sol
index 9f95960..109837b 100644
--- a/code/celo101-code-chapter_2/2-7-transactions-and-erc20-interface/marketplace.sol
+++ b/code/celo101-code-chapter_2/2-7-transactions-and-erc20-interface/marketplace.sol
@@ -29,7 +29,7 @@ contract Marketplace {
         uint sold;
     }
 
-    mapping (uint => Product) internal products;
+    mapping (uint => Product) private products;
 
     function writeProduct(
         string memory _name,
@@ -37,7 +37,7 @@ contract Marketplace {
         string memory _description, 
         string memory _location, 
         uint _price
-    ) public {
+    ) public external {
         uint _sold = 0;
         products[productsLength] = Product(
             payable(msg.sender),
@@ -71,7 +71,7 @@ contract Marketplace {
         );
     }
 
-    function buyProduct(uint _index) public payable  {
+    function buyProduct(uint _index) public external payable  {
         require(
           IERC20Token(cUsdTokenAddress).transferFrom(
             msg.sender,
@@ -86,4 +86,4 @@ contract Marketplace {
     function getProductsLength() public view returns (uint) {
         return (productsLength);
     }
-}
\ No newline at end of file
+}