diff --git a/src/Makefile.am b/src/Makefile.am
index e542a067a47..8905c0ad1cd 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -186,6 +186,7 @@ BITCOIN_CORE_H = \
   kernel/coinstats.h \
   kernel/context.h \
   kernel/cs_main.h \
+  kernel/disconnected_transactions.h \
   kernel/mempool_entry.h \
   kernel/mempool_limits.h \
   kernel/mempool_options.h \
diff --git a/src/Makefile.bench.include b/src/Makefile.bench.include
index 934e9a1fae1..28b779a5a88 100644
--- a/src/Makefile.bench.include
+++ b/src/Makefile.bench.include
@@ -28,6 +28,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/data.cpp \
   bench/data.h \
   bench/descriptors.cpp \
+  bench/disconnected_transactions.cpp \
   bench/duplicate_inputs.cpp \
   bench/ellswift.cpp \
   bench/examples.cpp \
diff --git a/src/bench/disconnected_transactions.cpp b/src/bench/disconnected_transactions.cpp
new file mode 100644
index 00000000000..d6f15909505
--- /dev/null
+++ b/src/bench/disconnected_transactions.cpp
@@ -0,0 +1,130 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <bench/bench.h>
+#include <kernel/disconnected_transactions.h>
+#include <primitives/block.h>
+#include <test/util/random.h>
+#include <test/util/setup_common.h>
+
+constexpr size_t BLOCK_VTX_COUNT{4000};
+constexpr size_t BLOCK_VTX_COUNT_10PERCENT{400};
+
+using BlockTxns = decltype(CBlock::vtx);
+
+/** Reorg where 1 block is disconnected and 2 blocks are connected. */
+struct ReorgTxns {
+    /** Disconnected block. */
+    BlockTxns disconnected_txns;
+    /** First connected block. */
+    BlockTxns connected_txns_1;
+    /** Second connected block, new chain tip. Has no overlap with disconnected_txns. */
+    BlockTxns connected_txns_2;
+    /** Transactions shared between disconnected_txns and connected_txns_1. */
+    size_t num_shared;
+};
+
+static BlockTxns CreateRandomTransactions(size_t num_txns)
+{
+    // Ensure every transaction has a different txid by having each one spend the previous one.
+    static uint256 prevout_hash{uint256::ZERO};
+
+    BlockTxns txns;
+    txns.reserve(num_txns);
+    // Simplest spk for every tx
+    CScript spk = CScript() << OP_TRUE;
+    for (uint32_t i = 0; i < num_txns; ++i) {
+        CMutableTransaction tx;
+        tx.vin.emplace_back(CTxIn{COutPoint{prevout_hash, 0}});
+        tx.vout.emplace_back(CTxOut{CENT, spk});
+        auto ptx{MakeTransactionRef(tx)};
+        txns.emplace_back(ptx);
+        prevout_hash = ptx->GetHash();
+    }
+    return txns;
+}
+
+/** Creates blocks for a Reorg, each with BLOCK_VTX_COUNT transactions. Between the disconnected
+ * block and the first connected block, there will be num_not_shared transactions that are
+ * different, and all other transactions the exact same. The second connected block has all unique
+ * transactions. This is to simulate a reorg in which all but num_not_shared transactions are
+ * confirmed in the new chain. */
+static ReorgTxns CreateBlocks(size_t num_not_shared)
+{
+    auto num_shared{BLOCK_VTX_COUNT - num_not_shared};
+    const auto shared_txns{CreateRandomTransactions(/*num_txns=*/num_shared)};
+
+    // Create different sets of transactions...
+    auto disconnected_block_txns{CreateRandomTransactions(/*num_txns=*/num_not_shared)};
+    std::copy(shared_txns.begin(), shared_txns.end(), std::back_inserter(disconnected_block_txns));
+
+    auto connected_block_txns{CreateRandomTransactions(/*num_txns=*/num_not_shared)};
+    std::copy(shared_txns.begin(), shared_txns.end(), std::back_inserter(connected_block_txns));
+
+    assert(disconnected_block_txns.size() == BLOCK_VTX_COUNT);
+    assert(connected_block_txns.size() == BLOCK_VTX_COUNT);
+
+    return ReorgTxns{/*disconnected_txns=*/disconnected_block_txns,
+                     /*connected_txns_1=*/connected_block_txns,
+                     /*connected_txns_2=*/CreateRandomTransactions(BLOCK_VTX_COUNT),
+                     /*num_shared=*/num_shared};
+}
+
+static void Reorg(const ReorgTxns& reorg)
+{
+    DisconnectedBlockTransactions disconnectpool{MAX_DISCONNECTED_TX_POOL_SIZE * 1000};
+    // Disconnect block
+    const auto evicted = disconnectpool.AddTransactionsFromBlock(reorg.disconnected_txns);
+    assert(evicted.empty());
+
+    // Connect first block
+    disconnectpool.removeForBlock(reorg.connected_txns_1);
+    // Connect new tip
+    disconnectpool.removeForBlock(reorg.connected_txns_2);
+
+    // Sanity Check
+    assert(disconnectpool.size() == BLOCK_VTX_COUNT - reorg.num_shared);
+
+    disconnectpool.clear();
+}
+
+/** Add transactions from DisconnectedBlockTransactions, remove all but one (the disconnected
+ * block's coinbase transaction) of them, and then pop from the front until empty. This is a reorg
+ * in which all of the non-coinbase transactions in the disconnected chain also exist in the new
+ * chain. */
+static void AddAndRemoveDisconnectedBlockTransactionsAll(benchmark::Bench& bench)
+{
+    const auto chains{CreateBlocks(/*num_not_shared=*/1)};
+    assert(chains.num_shared == BLOCK_VTX_COUNT - 1);
+
+    bench.minEpochIterations(10).run([&]() NO_THREAD_SAFETY_ANALYSIS {
+        Reorg(chains);
+    });
+}
+
+/** Add transactions from DisconnectedBlockTransactions, remove 90% of them, and then pop from the front until empty. */
+static void AddAndRemoveDisconnectedBlockTransactions90(benchmark::Bench& bench)
+{
+    const auto chains{CreateBlocks(/*num_not_shared=*/BLOCK_VTX_COUNT_10PERCENT)};
+    assert(chains.num_shared == BLOCK_VTX_COUNT - BLOCK_VTX_COUNT_10PERCENT);
+
+    bench.minEpochIterations(10).run([&]() NO_THREAD_SAFETY_ANALYSIS {
+        Reorg(chains);
+    });
+}
+
+/** Add transactions from DisconnectedBlockTransactions, remove 10% of them, and then pop from the front until empty. */
+static void AddAndRemoveDisconnectedBlockTransactions10(benchmark::Bench& bench)
+{
+    const auto chains{CreateBlocks(/*num_not_shared=*/BLOCK_VTX_COUNT - BLOCK_VTX_COUNT_10PERCENT)};
+    assert(chains.num_shared == BLOCK_VTX_COUNT_10PERCENT);
+
+    bench.minEpochIterations(10).run([&]() NO_THREAD_SAFETY_ANALYSIS {
+        Reorg(chains);
+    });
+}
+
+BENCHMARK(AddAndRemoveDisconnectedBlockTransactionsAll, benchmark::PriorityLevel::HIGH);
+BENCHMARK(AddAndRemoveDisconnectedBlockTransactions90, benchmark::PriorityLevel::HIGH);
+BENCHMARK(AddAndRemoveDisconnectedBlockTransactions10, benchmark::PriorityLevel::HIGH);
diff --git a/src/kernel/disconnected_transactions.h b/src/kernel/disconnected_transactions.h
new file mode 100644
index 00000000000..7db39ba5cae
--- /dev/null
+++ b/src/kernel/disconnected_transactions.h
@@ -0,0 +1,137 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_KERNEL_DISCONNECTED_TRANSACTIONS_H
+#define BITCOIN_KERNEL_DISCONNECTED_TRANSACTIONS_H
+
+#include <core_memusage.h>
+#include <memusage.h>
+#include <primitives/transaction.h>
+#include <util/hasher.h>
+
+#include <list>
+#include <unordered_map>
+#include <vector>
+
+/** Maximum kilobytes for transactions to store for processing during reorg */
+static const unsigned int MAX_DISCONNECTED_TX_POOL_SIZE = 20'000;
+/**
+ * DisconnectedBlockTransactions
+
+ * During the reorg, it's desirable to re-add previously confirmed transactions
+ * to the mempool, so that anything not re-confirmed in the new chain is
+ * available to be mined. However, it's more efficient to wait until the reorg
+ * is complete and process all still-unconfirmed transactions at that time,
+ * since we expect most confirmed transactions to (typically) still be
+ * confirmed in the new chain, and re-accepting to the memory pool is expensive
+ * (and therefore better to not do in the middle of reorg-processing).
+ * Instead, store the disconnected transactions (in order!) as we go, remove any
+ * that are included in blocks in the new chain, and then process the remaining
+ * still-unconfirmed transactions at the end.
+ *
+ * Order of queuedTx:
+ * The front of the list should be the most recently-confirmed transactions (transactions at the
+ * end of vtx of blocks closer to the tip). If memory usage grows too large, we trim from the front
+ * of the list. After trimming, transactions can be re-added to the mempool from the back of the
+ * list to the front without running into missing inputs.
+ */
+class DisconnectedBlockTransactions {
+private:
+    /** Cached dynamic memory usage for the CTransactions (memory for the shared pointers is
+     * included in the container calculations). */
+    uint64_t cachedInnerUsage = 0;
+    const size_t m_max_mem_usage;
+    std::list<CTransactionRef> queuedTx;
+    using TxList = decltype(queuedTx);
+    std::unordered_map<uint256, TxList::iterator, SaltedTxidHasher> iters_by_txid;
+
+    /** Trim the earliest-added entries until we are within memory bounds. */
+    std::vector<CTransactionRef> LimitMemoryUsage()
+    {
+        std::vector<CTransactionRef> evicted;
+
+        while (!queuedTx.empty() && DynamicMemoryUsage() > m_max_mem_usage) {
+            evicted.emplace_back(queuedTx.front());
+            cachedInnerUsage -= RecursiveDynamicUsage(*queuedTx.front());
+            iters_by_txid.erase(queuedTx.front()->GetHash());
+            queuedTx.pop_front();
+        }
+        return evicted;
+    }
+
+public:
+    DisconnectedBlockTransactions(size_t max_mem_usage) : m_max_mem_usage{max_mem_usage} {}
+
+    // It's almost certainly a logic bug if we don't clear out queuedTx before
+    // destruction, as we add to it while disconnecting blocks, and then we
+    // need to re-process remaining transactions to ensure mempool consistency.
+    // For now, assert() that we've emptied out this object on destruction.
+    // This assert() can always be removed if the reorg-processing code were
+    // to be refactored such that this assumption is no longer true (for
+    // instance if there was some other way we cleaned up the mempool after a
+    // reorg, besides draining this object).
+    ~DisconnectedBlockTransactions() {
+        assert(queuedTx.empty());
+        assert(iters_by_txid.empty());
+        assert(cachedInnerUsage == 0);
+    }
+
+    size_t DynamicMemoryUsage() const {
+        return cachedInnerUsage + memusage::DynamicUsage(iters_by_txid) + memusage::DynamicUsage(queuedTx);
+    }
+
+    /** Add transactions from the block, iterating through vtx in reverse order. Callers should call
+     * this function for blocks in descending order by block height.
+     * We assume that callers never pass multiple transactions with the same txid, otherwise things
+     * can go very wrong in removeForBlock due to queuedTx containing an item without a
+     * corresponding entry in iters_by_txid.
+     * @returns vector of transactions that were evicted for size-limiting.
+     */
+    [[nodiscard]] std::vector<CTransactionRef> AddTransactionsFromBlock(const std::vector<CTransactionRef>& vtx)
+    {
+        iters_by_txid.reserve(iters_by_txid.size() + vtx.size());
+        for (auto block_it = vtx.rbegin(); block_it != vtx.rend(); ++block_it) {
+            auto it = queuedTx.insert(queuedTx.end(), *block_it);
+            iters_by_txid.emplace((*block_it)->GetHash(), it);
+            cachedInnerUsage += RecursiveDynamicUsage(**block_it);
+        }
+        return LimitMemoryUsage();
+    }
+
+    /** Remove any entries that are in this block. */
+    void removeForBlock(const std::vector<CTransactionRef>& vtx)
+    {
+        // Short-circuit in the common case of a block being added to the tip
+        if (queuedTx.empty()) {
+            return;
+        }
+        for (const auto& tx : vtx) {
+            auto iter = iters_by_txid.find(tx->GetHash());
+            if (iter != iters_by_txid.end()) {
+                auto list_iter = iter->second;
+                iters_by_txid.erase(iter);
+                cachedInnerUsage -= RecursiveDynamicUsage(**list_iter);
+                queuedTx.erase(list_iter);
+            }
+        }
+    }
+
+    size_t size() const { return queuedTx.size(); }
+
+    void clear()
+    {
+        cachedInnerUsage = 0;
+        iters_by_txid.clear();
+        queuedTx.clear();
+    }
+
+    /** Clear all data structures and return the list of transactions. */
+    std::list<CTransactionRef> take()
+    {
+        std::list<CTransactionRef> ret = std::move(queuedTx);
+        clear();
+        return ret;
+    }
+};
+#endif // BITCOIN_KERNEL_DISCONNECTED_TRANSACTIONS_H
diff --git a/src/memusage.h b/src/memusage.h
index bb39066a7df..08be66172e3 100644
--- a/src/memusage.h
+++ b/src/memusage.h
@@ -11,6 +11,7 @@
 
 #include <cassert>
 #include <cstdlib>
+#include <list>
 #include <map>
 #include <memory>
 #include <set>
@@ -148,6 +149,21 @@ static inline size_t DynamicUsage(const std::shared_ptr<X>& p)
     return p ? MallocUsage(sizeof(X)) + MallocUsage(sizeof(stl_shared_counter)) : 0;
 }
 
+template<typename X>
+struct list_node
+{
+private:
+    void* ptr_next;
+    void* ptr_prev;
+    X x;
+};
+
+template<typename X>
+static inline size_t DynamicUsage(const std::list<X>& l)
+{
+    return MallocUsage(sizeof(list_node<X>)) * l.size();
+}
+
 template<typename X>
 struct unordered_node : private X
 {
diff --git a/src/test/validation_chainstatemanager_tests.cpp b/src/test/validation_chainstatemanager_tests.cpp
index 9e359eeee41..7b7be4be9ee 100644
--- a/src/test/validation_chainstatemanager_tests.cpp
+++ b/src/test/validation_chainstatemanager_tests.cpp
@@ -4,6 +4,7 @@
 //
 #include <chainparams.h>
 #include <consensus/validation.h>
+#include <kernel/disconnected_transactions.h>
 #include <node/kernel_notifications.h>
 #include <node/utxo_snapshot.h>
 #include <random.h>
@@ -536,7 +537,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_init, SnapshotTestSetup)
     // it will initialize instead of attempting to complete validation.
     //
     // Note that this is not a realistic use of DisconnectTip().
-    DisconnectedBlockTransactions unused_pool;
+    DisconnectedBlockTransactions unused_pool{MAX_DISCONNECTED_TX_POOL_SIZE * 1000};
     BlockValidationState unused_state;
     {
         LOCK2(::cs_main, bg_chainstate.MempoolMutex());
diff --git a/src/txmempool.h b/src/txmempool.h
index 8ea3373cb47..cbeabb31fa6 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -848,96 +848,4 @@ class CCoinsViewMemPool : public CCoinsViewBacked
     /** Clear m_temp_added and m_non_base_coins. */
     void Reset();
 };
-
-/**
- * DisconnectedBlockTransactions
-
- * During the reorg, it's desirable to re-add previously confirmed transactions
- * to the mempool, so that anything not re-confirmed in the new chain is
- * available to be mined. However, it's more efficient to wait until the reorg
- * is complete and process all still-unconfirmed transactions at that time,
- * since we expect most confirmed transactions to (typically) still be
- * confirmed in the new chain, and re-accepting to the memory pool is expensive
- * (and therefore better to not do in the middle of reorg-processing).
- * Instead, store the disconnected transactions (in order!) as we go, remove any
- * that are included in blocks in the new chain, and then process the remaining
- * still-unconfirmed transactions at the end.
- */
-
-// multi_index tag names
-struct txid_index {};
-struct insertion_order {};
-
-struct DisconnectedBlockTransactions {
-    typedef boost::multi_index_container<
-        CTransactionRef,
-        boost::multi_index::indexed_by<
-            // sorted by txid
-            boost::multi_index::hashed_unique<
-                boost::multi_index::tag<txid_index>,
-                mempoolentry_txid,
-                SaltedTxidHasher
-            >,
-            // sorted by order in the blockchain
-            boost::multi_index::sequenced<
-                boost::multi_index::tag<insertion_order>
-            >
-        >
-    > indexed_disconnected_transactions;
-
-    // It's almost certainly a logic bug if we don't clear out queuedTx before
-    // destruction, as we add to it while disconnecting blocks, and then we
-    // need to re-process remaining transactions to ensure mempool consistency.
-    // For now, assert() that we've emptied out this object on destruction.
-    // This assert() can always be removed if the reorg-processing code were
-    // to be refactored such that this assumption is no longer true (for
-    // instance if there was some other way we cleaned up the mempool after a
-    // reorg, besides draining this object).
-    ~DisconnectedBlockTransactions() { assert(queuedTx.empty()); }
-
-    indexed_disconnected_transactions queuedTx;
-    uint64_t cachedInnerUsage = 0;
-
-    // Estimate the overhead of queuedTx to be 6 pointers + an allocation, as
-    // no exact formula for boost::multi_index_contained is implemented.
-    size_t DynamicMemoryUsage() const {
-        return memusage::MallocUsage(sizeof(CTransactionRef) + 6 * sizeof(void*)) * queuedTx.size() + cachedInnerUsage;
-    }
-
-    void addTransaction(const CTransactionRef& tx)
-    {
-        queuedTx.insert(tx);
-        cachedInnerUsage += RecursiveDynamicUsage(tx);
-    }
-
-    // Remove entries based on txid_index, and update memory usage.
-    void removeForBlock(const std::vector<CTransactionRef>& vtx)
-    {
-        // Short-circuit in the common case of a block being added to the tip
-        if (queuedTx.empty()) {
-            return;
-        }
-        for (auto const &tx : vtx) {
-            auto it = queuedTx.find(tx->GetHash());
-            if (it != queuedTx.end()) {
-                cachedInnerUsage -= RecursiveDynamicUsage(*it);
-                queuedTx.erase(it);
-            }
-        }
-    }
-
-    // Remove an entry by insertion_order index, and update memory usage.
-    void removeEntry(indexed_disconnected_transactions::index<insertion_order>::type::iterator entry)
-    {
-        cachedInnerUsage -= RecursiveDynamicUsage(*entry);
-        queuedTx.get<insertion_order>().erase(entry);
-    }
-
-    void clear()
-    {
-        cachedInnerUsage = 0;
-        queuedTx.clear();
-    }
-};
-
 #endif // BITCOIN_TXMEMPOOL_H
diff --git a/src/validation.cpp b/src/validation.cpp
index db3310c2c36..0ce29021959 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -22,6 +22,7 @@
 #include <flatfile.h>
 #include <hash.h>
 #include <kernel/chainparams.h>
+#include <kernel/disconnected_transactions.h>
 #include <kernel/mempool_entry.h>
 #include <kernel/messagestartchars.h>
 #include <kernel/notifications_interface.h>
@@ -81,8 +82,6 @@ using node::CBlockIndexWorkComparator;
 using node::fReindex;
 using node::SnapshotMetadata;
 
-/** Maximum kilobytes for transactions to store for processing during reorg */
-static const unsigned int MAX_DISCONNECTED_TX_POOL_SIZE = 20000;
 /** Time to wait between writing blocks/block index to disk. */
 static constexpr std::chrono::hours DATABASE_WRITE_INTERVAL{1};
 /** Time to wait between flushing chainstate to disk. */
@@ -297,28 +296,30 @@ void Chainstate::MaybeUpdateMempoolForReorg(
     AssertLockHeld(cs_main);
     AssertLockHeld(m_mempool->cs);
     std::vector<uint256> vHashUpdate;
-    // disconnectpool's insertion_order index sorts the entries from
-    // oldest to newest, but the oldest entry will be the last tx from the
-    // latest mined block that was disconnected.
-    // Iterate disconnectpool in reverse, so that we add transactions
-    // back to the mempool starting with the earliest transaction that had
-    // been previously seen in a block.
-    auto it = disconnectpool.queuedTx.get<insertion_order>().rbegin();
-    while (it != disconnectpool.queuedTx.get<insertion_order>().rend()) {
-        // ignore validation errors in resurrected transactions
-        if (!fAddToMempool || (*it)->IsCoinBase() ||
-            AcceptToMemoryPool(*this, *it, GetTime(),
-                /*bypass_limits=*/true, /*test_accept=*/false).m_result_type !=
-                    MempoolAcceptResult::ResultType::VALID) {
-            // If the transaction doesn't make it in to the mempool, remove any
-            // transactions that depend on it (which would now be orphans).
-            m_mempool->removeRecursive(**it, MemPoolRemovalReason::REORG);
-        } else if (m_mempool->exists(GenTxid::Txid((*it)->GetHash()))) {
-            vHashUpdate.push_back((*it)->GetHash());
-        }
-        ++it;
-    }
-    disconnectpool.queuedTx.clear();
+    {
+        // disconnectpool is ordered so that the front is the most recently-confirmed
+        // transaction (the last tx of the block at the tip) in the disconnected chain.
+        // Iterate disconnectpool in reverse, so that we add transactions
+        // back to the mempool starting with the earliest transaction that had
+        // been previously seen in a block.
+        const auto queuedTx = disconnectpool.take();
+        auto it = queuedTx.rbegin();
+        while (it != queuedTx.rend()) {
+            // ignore validation errors in resurrected transactions
+            if (!fAddToMempool || (*it)->IsCoinBase() ||
+                AcceptToMemoryPool(*this, *it, GetTime(),
+                    /*bypass_limits=*/true, /*test_accept=*/false).m_result_type !=
+                        MempoolAcceptResult::ResultType::VALID) {
+                // If the transaction doesn't make it in to the mempool, remove any
+                // transactions that depend on it (which would now be orphans).
+                m_mempool->removeRecursive(**it, MemPoolRemovalReason::REORG);
+            } else if (m_mempool->exists(GenTxid::Txid((*it)->GetHash()))) {
+                vHashUpdate.push_back((*it)->GetHash());
+            }
+            ++it;
+        }
+    }
+
     // AcceptToMemoryPool/addUnchecked all assume that new mempool entries have
     // no in-mempool children, which is generally not true when adding
     // previously-confirmed transactions back to the mempool.
@@ -2795,15 +2796,10 @@ bool Chainstate::DisconnectTip(BlockValidationState& state, DisconnectedBlockTra
     }
 
     if (disconnectpool && m_mempool) {
-        // Save transactions to re-add to mempool at end of reorg
-        for (auto it = block.vtx.rbegin(); it != block.vtx.rend(); ++it) {
-            disconnectpool->addTransaction(*it);
-        }
-        while (disconnectpool->DynamicMemoryUsage() > MAX_DISCONNECTED_TX_POOL_SIZE * 1000) {
-            // Drop the earliest entry, and remove its children from the mempool.
-            auto it = disconnectpool->queuedTx.get<insertion_order>().begin();
-            m_mempool->removeRecursive(**it, MemPoolRemovalReason::REORG);
-            disconnectpool->removeEntry(it);
+        // Save transactions to re-add to mempool at end of reorg. If any entries are evicted for
+        // exceeding memory limits, remove them and their descendants from the mempool.
+        for (auto&& evicted_tx : disconnectpool->AddTransactionsFromBlock(block.vtx)) {
+            m_mempool->removeRecursive(*evicted_tx, MemPoolRemovalReason::REORG);
         }
     }
 
@@ -3053,7 +3049,7 @@ bool Chainstate::ActivateBestChainStep(BlockValidationState& state, CBlockIndex*
 
     // Disconnect active blocks which are no longer in the best chain.
     bool fBlocksDisconnected = false;
-    DisconnectedBlockTransactions disconnectpool;
+    DisconnectedBlockTransactions disconnectpool{MAX_DISCONNECTED_TX_POOL_SIZE * 1000};
     while (m_chain.Tip() && m_chain.Tip() != pindexFork) {
         if (!DisconnectTip(state, &disconnectpool)) {
             // This is likely a fatal error, but keep the mempool consistent,
@@ -3387,7 +3383,7 @@ bool Chainstate::InvalidateBlock(BlockValidationState& state, CBlockIndex* pinde
 
         // ActivateBestChain considers blocks already in m_chain
         // unconditionally valid already, so force disconnect away from it.
-        DisconnectedBlockTransactions disconnectpool;
+        DisconnectedBlockTransactions disconnectpool{MAX_DISCONNECTED_TX_POOL_SIZE * 1000};
         bool ret = DisconnectTip(state, &disconnectpool);
         // DisconnectTip will add transactions to disconnectpool.
         // Adjust the mempool to be consistent with the new tip, adding
diff --git a/src/validation.h b/src/validation.h
index f1ff6bb6719..6640bb5b50a 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -50,7 +50,7 @@ class Chainstate;
 class CTxMemPool;
 class ChainstateManager;
 struct ChainTxData;
-struct DisconnectedBlockTransactions;
+class DisconnectedBlockTransactions;
 struct PrecomputedTransactionData;
 struct LockPoints;
 struct AssumeutxoData;