Updated solidity code to the pragma 0.4.24 compiler specification.

contracts/FixedSupplyToken.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.11;
+pragma solidity ^0.4.24;
 
 // ----------------------------------------------------------------------------------------------
 // Sample fixed supply token contract
@@ -59,7 +59,7 @@ contract FixedSupplyToken is ERC20Interface {
   }
 
   // Constructor
-  function FixedSupplyToken() public {
+  constructor() public {
     owner = msg.sender;
     balances[owner] = _totalSupply;
   }
@@ -78,7 +78,7 @@ contract FixedSupplyToken is ERC20Interface {
     if (balances[msg.sender] >= _amount && _amount > 0 && balances[_to] + _amount > balances[_to]) {
       balances[msg.sender] -= _amount;
       balances[_to] += _amount;
-      Transfer(msg.sender, _to, _amount);
+      emit Transfer(msg.sender, _to, _amount);
       return true;
     } else {
         return false;
@@ -100,7 +100,7 @@ contract FixedSupplyToken is ERC20Interface {
        balances[_from] -= _amount;
        allowed[_from][msg.sender] -= _amount;
        balances[_to] += _amount;
-       Transfer(_from, _to, _amount);
+       emit Transfer(_from, _to, _amount);
        return true;
     } else {
       return false;
@@ -111,11 +111,11 @@ contract FixedSupplyToken is ERC20Interface {
   // If this function is called again it overwrites the current allowance with _value.
   function approve(address _spender, uint256 _amount) public returns (bool success) {
     allowed[msg.sender][_spender] = _amount;
-    Approval(msg.sender, _spender, _amount);
+    emit Approval(msg.sender, _spender, _amount);
     return true;
   }
 
   function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
     return allowed[_owner][_spender];
   }
-}
+}

contracts/Forwarder.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.18;
+pragma solidity ^0.4.24;
 import "./ERC20Interface.sol";
 /**
  * Contract that will forward any incoming Ether to the creator of the contract
@@ -11,7 +11,7 @@ contract Forwarder {
   /**
    * Create the contract, and sets the destination address to that of the creator
    */
-  function Forwarder() public {
+  constructor() public {
     parentAddress = msg.sender;
   }
 
@@ -32,7 +32,7 @@ contract Forwarder {
     // throws on failure
     parentAddress.transfer(msg.value);
     // Fire off the deposited event if we can forward it
-    ForwarderDeposited(msg.sender, msg.value, msg.data);
+    emit ForwarderDeposited(msg.sender, msg.value, msg.data);
   }
 
   /**
@@ -41,8 +41,8 @@ contract Forwarder {
    */
   function flushTokens(address tokenContractAddress) public onlyParent {
     ERC20Interface instance = ERC20Interface(tokenContractAddress);
-    var forwarderAddress = address(this);
-    var forwarderBalance = instance.balanceOf(forwarderAddress);
+    address forwarderAddress = address(this);
+    uint256 forwarderBalance = instance.balanceOf(forwarderAddress);
     if (forwarderBalance == 0) {
       return;
     }
@@ -57,6 +57,6 @@ contract Forwarder {
    */
   function flush() public {
     // throws on failure
-    parentAddress.transfer(this.balance);
+    parentAddress.transfer(address(this).balance);
   }
 }

contracts/ForwarderTarget.sol

@@ -1,14 +1,14 @@
-pragma solidity ^0.4.18;
+pragma solidity ^0.4.24;
 
 
 import "./Forwarder.sol";
 
 // This is a test target for a Forwarder.
 // It contains a public function with a side-effect.
 contract ForwarderTarget {
-  uint public data;
+  uint256 public data;
 
-  function ForwarderTarget() public {
+  constructor() public {
   }
 
   function setDataWithValue(uint d, bool b) payable public returns (bool) {

contracts/WalletSimple.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.18;
+pragma solidity ^0.4.24;
 import "./Forwarder.sol";
 import "./ERC20Interface.sol";
 /**
@@ -56,7 +56,7 @@ contract WalletSimple {
    *
    * @param allowedSigners An array of signers on the wallet
    */
-  function WalletSimple(address[] allowedSigners) public {
+  constructor(address[] allowedSigners) public {
     if (allowedSigners.length != 3) {
       // Invalid number of signers
       revert();
@@ -95,7 +95,7 @@ contract WalletSimple {
   function() public payable {
     if (msg.value > 0) {
       // Fire deposited event if we are receiving funds
-      Deposited(msg.sender, msg.value, msg.data);
+      emit Deposited(msg.sender, msg.value, msg.data);
     }
   }
 
@@ -127,16 +127,16 @@ contract WalletSimple {
       bytes signature
   ) public onlySigner {
     // Verify the other signer
-    var operationHash = keccak256("ETHER", toAddress, value, data, expireTime, sequenceId);
+    bytes32 operationHash = keccak256(abi.encodePacked("ETHER", toAddress, value, data, expireTime, sequenceId));
 
-    var otherSigner = verifyMultiSig(toAddress, operationHash, signature, expireTime, sequenceId);
+    address otherSigner = verifyMultiSig(toAddress, operationHash, signature, expireTime, sequenceId);
 
     // Success, send the transaction
     if (!(toAddress.call.value(value)(data))) {
       // Failed executing transaction
       revert();
     }
-    Transacted(msg.sender, otherSigner, operationHash, toAddress, value, data);
+    emit Transacted(msg.sender, otherSigner, operationHash, toAddress, value, data);
   }
 
   /**
@@ -159,7 +159,7 @@ contract WalletSimple {
       bytes signature
   ) public onlySigner {
     // Verify the other signer
-    var operationHash = keccak256("ERC20", toAddress, value, tokenContractAddress, expireTime, sequenceId);
+    bytes32 operationHash = keccak256(abi.encodePacked("ERC20", toAddress, value, tokenContractAddress, expireTime, sequenceId));
 
     verifyMultiSig(toAddress, operationHash, signature, expireTime, sequenceId);
 
@@ -201,7 +201,7 @@ contract WalletSimple {
       uint sequenceId
   ) private returns (address) {
 
-    var otherSigner = recoverAddressFromSignature(operationHash, signature);
+    address otherSigner = recoverAddressFromSignature(operationHash, signature);
 
     // Verify if we are in safe mode. In safe mode, the wallet can only send to signers
     if (safeMode && !isSigner(toAddress)) {
@@ -234,7 +234,7 @@ contract WalletSimple {
    */
   function activateSafeMode() public onlySigner {
     safeMode = true;
-    SafeModeActivated(msg.sender);
+    emit SafeModeActivated(msg.sender);
   }
 
   /**