diff --git a/.gas-snapshot b/.gas-snapshot
index b48b480..ae5272d 100644
--- a/.gas-snapshot
+++ b/.gas-snapshot
@@ -8,10 +8,10 @@ ERC6909Test:testBalanceOf() (gas: 17504)
 ERC6909Test:testSetOperator() (gas: 42429)
 ERC6909Test:testSupportsInterface() (gas: 6703)
 ERC6909Test:testTotalSupply() (gas: 9874)
-ERC6909Test:testTransfer() (gas: 48795)
-ERC6909Test:testTransferFrom() (gas: 65198)
-ERC6909Test:testTransferFromCallerIsOperator() (gas: 78223)
-ERC6909Test:testTransferFromCallerIsSpender() (gas: 49295)
-ERC6909Test:testTransferFromInsufficientBalance() (gas: 23767)
-ERC6909Test:testTransferFromInsufficientPermission() (gas: 29792)
-ERC6909Test:testTransferInsufficientBalance() (gas: 23357)
\ No newline at end of file
+ERC6909Test:testTransfer() (gas: 48420)
+ERC6909Test:testTransferFrom() (gas: 64584)
+ERC6909Test:testTransferFromCallerIsOperator() (gas: 77803)
+ERC6909Test:testTransferFromCallerIsSpender() (gas: 48875)
+ERC6909Test:testTransferFromInsufficientBalance() (gas: 22824)
+ERC6909Test:testTransferFromInsufficientPermission() (gas: 28868)
+ERC6909Test:testTransferInsufficientBalance() (gas: 22441)
\ No newline at end of file
diff --git a/src/ERC6909.sol b/src/ERC6909.sol
index c34b4b9..936f016 100644
--- a/src/ERC6909.sol
+++ b/src/ERC6909.sol
@@ -4,16 +4,6 @@ pragma solidity ^0.8.19;
 import "src/interfaces/IERC6909.sol";
 
 contract ERC6909 is IERC6909 {
-    /// @dev Thrown when owner balance for id is insufficient.
-    /// @param owner The address of the owner.
-    /// @param id The id of the token.
-    error InsufficientBalance(address owner, uint256 id);
-
-    /// @dev Thrown when spender allowance for id is insufficient.
-    /// @param spender The address of the spender.
-    /// @param id The id of the token.
-    error InsufficientPermission(address spender, uint256 id);
-
     /// @notice The total supply of each id.
     mapping(uint256 id => uint256 amount) public totalSupply;
 
@@ -31,9 +21,14 @@ contract ERC6909 is IERC6909 {
     /// @param id The id of the token.
     /// @param amount The amount of the token.
     function transfer(address receiver, uint256 id, uint256 amount) public {
-        if (balanceOf[msg.sender][id] < amount) revert InsufficientBalance(msg.sender, id);
         balanceOf[msg.sender][id] -= amount;
-        balanceOf[receiver][id] += amount;
+        
+        // Cannot overflow because the sum of all user
+        // balances can't exceed the max uint256 value.
+        unchecked {
+            balanceOf[receiver][id] += amount;
+        }
+
         emit Transfer(msg.sender, receiver, id, amount);
     }
 
@@ -44,14 +39,17 @@ contract ERC6909 is IERC6909 {
     /// @param amount The amount of the token.
     function transferFrom(address sender, address receiver, uint256 id, uint256 amount) public {
         if (sender != msg.sender && !isOperator[sender][msg.sender]) {
-            if (allowance[sender][msg.sender][id] < amount) {
-                revert InsufficientPermission(msg.sender, id);
-            }
             allowance[sender][msg.sender][id] -= amount;
         }
-        if (balanceOf[sender][id] < amount) revert InsufficientBalance(sender, id);
+        
         balanceOf[sender][id] -= amount;
-        balanceOf[receiver][id] += amount;
+
+        // Cannot overflow because the sum of all user
+        // balances can't exceed the max uint256 value.
+        unchecked {
+            balanceOf[receiver][id] += amount;
+        }
+        
         emit Transfer(sender, receiver, id, amount);
     }
 
diff --git a/test/ERC6909.t.sol b/test/ERC6909.t.sol
index 9f9ff41..8861f67 100644
--- a/test/ERC6909.t.sol
+++ b/test/ERC6909.t.sol
@@ -131,7 +131,7 @@ contract ERC6909Test is Test {
     function testTransferInsufficientBalance() public {
         assertEq(erc6909.balanceOf(alice, tokenId), 1);
         assertEq(erc6909.balanceOf(bob, tokenId), 0);
-        vm.expectRevert(abi.encodeWithSelector(InsufficientBalance.selector, alice, tokenId));
+        vm.expectRevert();
 
         vm.prank(alice);
         erc6909.transfer(bob, tokenId, 2);
@@ -140,7 +140,7 @@ contract ERC6909Test is Test {
     function testTransferFromInsufficientBalance() public {
         assertEq(erc6909.balanceOf(alice, tokenId), 1);
         assertEq(erc6909.balanceOf(bob, tokenId), 0);
-        vm.expectRevert(abi.encodeWithSelector(InsufficientBalance.selector, alice, tokenId));
+        vm.expectRevert();
 
         vm.prank(alice);
         erc6909.transferFrom(alice, bob, tokenId, 2);
@@ -150,7 +150,7 @@ contract ERC6909Test is Test {
         assertEq(erc6909.balanceOf(alice, tokenId), 1);
         assertEq(erc6909.balanceOf(bob, tokenId), 0);
         assertEq(erc6909.allowance(alice, bob, tokenId), 0);
-        vm.expectRevert(abi.encodeWithSelector(InsufficientPermission.selector, bob, tokenId));
+        vm.expectRevert();
 
         vm.prank(bob);
         erc6909.transferFrom(alice, bob, tokenId, 1);