diff --git a/onchain/ProvethVerifier.sol b/onchain/ProvethVerifier.sol
index 5af77db..e705f95 100644
--- a/onchain/ProvethVerifier.sol
+++ b/onchain/ProvethVerifier.sol
@@ -419,5 +419,8 @@ contract ProvethVerifier {
                 }
             }
         }
+
+        // If we reach here, the proof traversal was incomplete
+        revert("Invalid proof: incomplete traversal");
     }
 }