diff --git a/MyAdvancedToken.sol b/MyAdvancedToken.sol
index f8af15d..bea9d20 100644
--- a/MyAdvancedToken.sol
+++ b/MyAdvancedToken.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.4.16;
+pragma solidity ^0.4.20;
 
 
 import "./owned.sol";
@@ -19,7 +19,7 @@ contract MyAdvancedToken is owned, TokenERC20 {
     event FrozenFunds(address target, bool frozen);
 
     /* Initializes contract with initial supply tokens to the creator of the contract */
-    function MyAdvancedToken(
+    constructor (
         uint256 initialSupply,
         string tokenName,
         string tokenSymbol
@@ -34,7 +34,7 @@ contract MyAdvancedToken is owned, TokenERC20 {
         require(!frozenAccount[_to]);                       // Check if recipient is frozen
         balanceOf[_from] -= _value;                         // Subtract from the sender
         balanceOf[_to] += _value;                           // Add the same to the recipient
-        Transfer(_from, _to, _value);
+        emit Transfer(_from, _to, _value);
     }
 
     /// @notice Create `mintedAmount` tokens and send it to `target`
@@ -43,8 +43,8 @@ contract MyAdvancedToken is owned, TokenERC20 {
     function mintToken(address target, uint256 mintedAmount) onlyOwner public {
         balanceOf[target] += mintedAmount;
         totalSupply += mintedAmount;
-        Transfer(0, this, mintedAmount);
-        Transfer(this, target, mintedAmount);
+        emit Transfer(0, this, mintedAmount);
+        emit Transfer(this, target, mintedAmount);
     }
 
     /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
@@ -52,7 +52,7 @@ contract MyAdvancedToken is owned, TokenERC20 {
     /// @param freeze either to freeze it or not
     function freezeAccount(address target, bool freeze) onlyOwner public {
         frozenAccount[target] = freeze;
-        FrozenFunds(target, freeze);
+        emit FrozenFunds(target, freeze);
     }
 
     /// @notice Allow users to buy tokens for `newBuyPrice` eth and sell tokens for `newSellPrice` eth
diff --git a/TokenERC20.sol b/TokenERC20.sol
index 1d57c12..e5f698d 100644
--- a/TokenERC20.sol
+++ b/TokenERC20.sol
@@ -1,6 +1,6 @@
-pragma solidity ^0.4.16;
+pragma solidity ^0.4.20;
 
-interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }
+interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }
 
 contract TokenERC20 {
     string public name;
@@ -22,7 +22,7 @@ contract TokenERC20 {
     /**
      * 初始化构造
      */
-    function TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol) public {
+    constructor(uint256 initialSupply, string tokenName, string tokenSymbol) public {
         totalSupply = initialSupply * 10 ** uint256(decimals);  // 供应的份额，份额跟最小的代币单位有关，份额 = 币数 * 10 ** decimals。
         balanceOf[msg.sender] = totalSupply;                // 创建者拥有所有的代币
         name = tokenName;                                   // 代币名称
@@ -46,7 +46,7 @@ contract TokenERC20 {
         balanceOf[_from] -= _value;
         // Add the same to the recipient
         balanceOf[_to] += _value;
-        Transfer(_from, _to, _value);
+        emit Transfer(_from, _to, _value);
 
         // 用assert来检查代码逻辑。
         assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
@@ -114,7 +114,7 @@ contract TokenERC20 {
         require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
         balanceOf[msg.sender] -= _value;            // Subtract from the sender
         totalSupply -= _value;                      // Updates totalSupply
-        Burn(msg.sender, _value);
+        emit Burn(msg.sender, _value);
         return true;
     }
 
@@ -132,7 +132,7 @@ contract TokenERC20 {
         balanceOf[_from] -= _value;                         // Subtract from the targeted balance
         allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
         totalSupply -= _value;                              // Update totalSupply
-        Burn(_from, _value);
+        emit Burn(_from, _value);
         return true;
     }
 }
diff --git a/owned.sol b/owned.sol
index 3f270bf..6976a3b 100644
--- a/owned.sol
+++ b/owned.sol
@@ -3,7 +3,7 @@ pragma solidity ^0.4.16;
 contract owned {
     address public owner;
 
-    function owned() public {
+    constructor() public {
         owner = msg.sender;
     }