diff --git a/contracts/Timelock.sol b/contracts/Timelock.sol
index 69dcf3c1c..51a6bf740 100644
--- a/contracts/Timelock.sol
+++ b/contracts/Timelock.sol
@@ -1,10 +1,7 @@
 // SPDX-License-Identifier: BSD-3-Clause
 pragma solidity ^0.8.10;
 
-import "./SafeMath.sol";
-
 contract Timelock {
-    using SafeMath for uint;
 
     event NewAdmin(address indexed newAdmin);
     event NewPendingAdmin(address indexed newPendingAdmin);
@@ -24,7 +21,7 @@ contract Timelock {
     mapping (bytes32 => bool) public queuedTransactions;
 
 
-    constructor(address admin_, uint delay_) public {
+    constructor(address admin_, uint delay_) {
         require(delay_ >= MINIMUM_DELAY, "Timelock::constructor: Delay must exceed minimum delay.");
         require(delay_ <= MAXIMUM_DELAY, "Timelock::setDelay: Delay must not exceed maximum delay.");
 
@@ -60,7 +57,7 @@ contract Timelock {
 
     function queueTransaction(address target, uint value, string memory signature, bytes memory data, uint eta) public returns (bytes32) {
         require(msg.sender == admin, "Timelock::queueTransaction: Call must come from admin.");
-        require(eta >= getBlockTimestamp().add(delay), "Timelock::queueTransaction: Estimated execution block must satisfy delay.");
+        require(eta >= getBlockTimestamp() + delay, "Timelock::queueTransaction: Estimated execution block must satisfy delay.");
 
         bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
         queuedTransactions[txHash] = true;
@@ -73,6 +70,8 @@ contract Timelock {
         require(msg.sender == admin, "Timelock::cancelTransaction: Call must come from admin.");
 
         bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
+        require(queuedTransactions[txHash], "Timelock::cancelTransaction: Transaction hasn't been queued.");
+
         queuedTransactions[txHash] = false;
 
         emit CancelTransaction(txHash, target, value, signature, data, eta);
@@ -84,7 +83,7 @@ contract Timelock {
         bytes32 txHash = keccak256(abi.encode(target, value, signature, data, eta));
         require(queuedTransactions[txHash], "Timelock::executeTransaction: Transaction hasn't been queued.");
         require(getBlockTimestamp() >= eta, "Timelock::executeTransaction: Transaction hasn't surpassed time lock.");
-        require(getBlockTimestamp() <= eta.add(GRACE_PERIOD), "Timelock::executeTransaction: Transaction is stale.");
+        require(getBlockTimestamp() <= eta + GRACE_PERIOD, "Timelock::executeTransaction: Transaction is stale.");
 
         queuedTransactions[txHash] = false;