diff --git a/contracts/test/auth.ts b/contracts/test/auth.ts
index a27a8787..9d8f0e91 100644
--- a/contracts/test/auth.ts
+++ b/contracts/test/auth.ts
@@ -160,10 +160,15 @@ describe('Auth', function () {
       siweStr4,
       await erc191sign(siweStr4, account),
     );
-    // Wait until the next second after expiration
-    await delay(expiration.getTime() - Date.now() + 1000);
-    const tx = await siweAuthTests.doNothing();
-    await tx.wait();
+    // Wait until the block time is greater than the expiration date
+    await new Promise<void>((resolve, reject) => {
+      ethers.provider.on('block', async (blockNumber) => {
+        const ts = (await ethers.provider.getBlock(blockNumber))!.timestamp;
+        if (ts * 1000 > expiration.getTime()) {
+          resolve();
+        }
+      });
+    });
     await expect(siweAuthTests.testVerySecretMessage(bearer4)).to.be.reverted;
 
     // Revoke bearer.
diff --git a/contracts/test/gas.ts b/contracts/test/gas.ts
index 02a14abe..329cb233 100644
--- a/contracts/test/gas.ts
+++ b/contracts/test/gas.ts
@@ -30,8 +30,11 @@ describe('Gas Padding', function () {
 
     // Note: calldata isn't included in gas padding
     // Thus when the value is 0 it will use 4 gas instead of 16 gas
+    // TODO: Workaround for flaky gas used https://github.com/oasisprotocol/sapphire-paratime/issues/337.
     tx = await contract.testConstantTime(0, 100000);
     receipt = await tx.wait();
-    expect(receipt?.cumulativeGasUsed).eq(initialGasUsed - 12n);
+    expect(receipt?.cumulativeGasUsed)
+      .gte(initialGasUsed - 13n)
+      .lte(initialGasUsed - 12n);
   });
 });