diff --git a/onchain/ProvethVerifier.sol b/onchain/ProvethVerifier.sol
index 5dbd34b..e7e2571 100644
--- a/onchain/ProvethVerifier.sol
+++ b/onchain/ProvethVerifier.sol
@@ -237,7 +237,7 @@ contract ProvethVerifier {
         bytes stackIndexes,
         RLP.RLPItem[] memory stack
     ) internal returns (bytes memory value) {
-        assert(stackIndexes.length == stack.length);
+        require(stackIndexes.length == stack.length);
 
         uint mptPathOffset = 0;