diff --git a/contracts/WETH9.sol b/contracts/WETH9.sol
index ebfa3316d..dfa7b0ea4 100644
--- a/contracts/WETH9.sol
+++ b/contracts/WETH9.sol
@@ -19,7 +19,7 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-pragma solidity ^0.7.0;
+pragma solidity ^0.8.0;
 
 contract WETH9 {
     string public name     = "Wrapped Ether";
@@ -46,7 +46,7 @@ contract WETH9 {
     function withdraw(uint wad) public {
         require(balanceOf[msg.sender] >= wad);
         balanceOf[msg.sender] -= wad;
-        msg.sender.transfer(wad);
+        payable(msg.sender).transfer(wad);
         emit Withdrawal(msg.sender, wad);
     }
 
@@ -70,7 +70,7 @@ contract WETH9 {
     {
         require(balanceOf[src] >= wad);
 
-        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
+        if (src != msg.sender && allowance[src][msg.sender] != type(uint256).max) {
             require(allowance[src][msg.sender] >= wad);
             allowance[src][msg.sender] -= wad;
         }