diff --git a/src/kernel/chainparams.cpp b/src/kernel/chainparams.cpp
index 4a747e7317c..6b64c79d05c 100644
--- a/src/kernel/chainparams.cpp
+++ b/src/kernel/chainparams.cpp
@@ -589,9 +589,9 @@ public:
             {
                 // For use by fuzz target src/test/fuzz/utxo_snapshot.cpp
                 .height = 200,
-                .hash_serialized = AssumeutxoHash{uint256{"7e3b7780fbd2fa479a01f66950dc8f728dc1b11f03d06d5bf223168520df3a48"}},
+                .hash_serialized = AssumeutxoHash{uint256{"17dcc016d188d16068907cdeb38b75691a118d43053b8cd6a25969419381d13a"}},
                 .m_chain_tx_count = 201,
-                .blockhash = consteval_ctor(uint256{"5e93653318f294fb5aa339d00bbf8cf1c3515488ad99412c37608b139ea63b27"}),
+                .blockhash = consteval_ctor(uint256{"385901ccbd69dff6bbd00065d01fb8a9e464dede7cfe0372443884f9b1dcf6b9"}),
             },
             {
                 // For use by test/functional/feature_assumeutxo.py
diff --git a/src/test/fuzz/utxo_total_supply.cpp b/src/test/fuzz/utxo_total_supply.cpp
index e574c5b85c5..9be85df99fa 100644
--- a/src/test/fuzz/utxo_total_supply.cpp
+++ b/src/test/fuzz/utxo_total_supply.cpp
@@ -52,6 +52,7 @@ FUZZ_TARGET(utxo_total_supply)
         // Replace OP_FALSE with OP_TRUE
         {
             CMutableTransaction tx{*block->vtx.back()};
+            tx.nLockTime = 0; // Use the same nLockTime for all as we want to duplicate one of them.
             tx.vout.at(0).scriptPubKey = CScript{} << OP_TRUE;
             block->vtx.back() = MakeTransactionRef(tx);
         }
diff --git a/src/test/util/mining.cpp b/src/test/util/mining.cpp
index 8baac7bba3e..1cd8f8ee718 100644
--- a/src/test/util/mining.cpp
+++ b/src/test/util/mining.cpp
@@ -17,6 +17,8 @@
 #include <validationinterface.h>
 #include <versionbits.h>
 
+#include <algorithm>
+
 using node::BlockAssembler;
 using node::NodeContext;
 
@@ -34,12 +36,15 @@ std::vector<std::shared_ptr<CBlock>> CreateBlockChain(size_t total_height, const
 {
     std::vector<std::shared_ptr<CBlock>> ret{total_height};
     auto time{params.GenesisBlock().nTime};
+    // NOTE: here `height` does not correspond to the block height but the block height - 1.
     for (size_t height{0}; height < total_height; ++height) {
         CBlock& block{*(ret.at(height) = std::make_shared<CBlock>())};
 
         CMutableTransaction coinbase_tx;
+        coinbase_tx.nLockTime = static_cast<uint32_t>(height);
         coinbase_tx.vin.resize(1);
         coinbase_tx.vin[0].prevout.SetNull();
+        coinbase_tx.vin[0].nSequence = CTxIn::MAX_SEQUENCE_NONFINAL; // Make sure timelock is enforced.
         coinbase_tx.vout.resize(1);
         coinbase_tx.vout[0].scriptPubKey = P2WSH_OP_TRUE;
         coinbase_tx.vout[0].nValue = GetBlockSubsidy(height + 1, params.GetConsensus());