diff --git a/test/DCO2s.t.sol b/test/DCO2s.t.sol
index 22db5bf..7d5fdbd 100644
--- a/test/DCO2s.t.sol
+++ b/test/DCO2s.t.sol
@@ -36,7 +36,8 @@ contract DCO2sTest is Test {
     }
 
     // @notice: checkFailed token Index
-    function testFailTokenIndex() public view {
+    function testRevertTokenIndex() public {
+        vm.expectRevert();
         dco2sc.tokenURI(0);
     }
 
@@ -106,7 +107,8 @@ contract DCO2sTest is Test {
     }
 
     // @notice: testFailMintToZeroAddress test that cannot safe mint to address 0
-    function testFailMintToZeroAddress() public {
+    function testRevertMintToZeroAddress() public {
+        vm.expectRevert();
         dco2sc.safeMint(address(0), nfts[0]);
     }