diff --git a/src/node/miner.cpp b/src/node/miner.cpp
index e8bfa973360fcf..e2d07612cf0e08 100644
--- a/src/node/miner.cpp
+++ b/src/node/miner.cpp
@@ -16,6 +16,7 @@
 #include <consensus/validation.h>
 #include <deploymentstatus.h>
 #include <logging.h>
+#include <mempool_set_definitions.h>
 #include <policy/feerate.h>
 #include <policy/policy.h>
 #include <pow.h>
@@ -35,6 +36,7 @@
 
 using MemPoolMultiIndex::ancestor_score;
 using MemPoolMultiIndex::CompareTxMemPoolEntryByAncestorFee;
+using MemPoolMultiIndex::indexed_transaction_set;
 using MemPoolMultiIndex::raw_txiter;
 
 // Container for tracking updates to ancestor feerate as we include (parent)
@@ -413,7 +415,7 @@ void BlockAssembler::addPackageTxs(const CTxMemPool& mempool, int& nPackagesSele
     // Keep track of entries that failed inclusion, to avoid duplicate work
     std::set<Txid> failedTx;
 
-    CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx->impl.get<ancestor_score>().begin();
+    indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx->impl.get<ancestor_score>().begin();
     raw_txiter iter;
 
     // Limit the number of attempts to add transactions to the block when it is
diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
index 91a3b0d97abac1..0d8297ce5e50d7 100644
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <common/system.h>
+#include <mempool_set_definitions.h>
 #include <policy/policy.h>
 #include <test/util/txmempool.h>
 #include <txmempool.h>
@@ -15,6 +16,7 @@
 
 using MemPoolMultiIndex::ancestor_score;
 using MemPoolMultiIndex::descendant_score;
+using MemPoolMultiIndex::indexed_transaction_set;
 
 BOOST_FIXTURE_TEST_SUITE(mempool_tests, TestingSetup)
 
@@ -122,7 +124,7 @@ template <typename name>
 static void CheckSort(CTxMemPool& pool, std::vector<std::string>& sortedOrder) EXCLUSIVE_LOCKS_REQUIRED(pool.cs)
 {
     BOOST_CHECK_EQUAL(pool.size(), sortedOrder.size());
-    typename CTxMemPool::indexed_transaction_set::index<name>::type::iterator it = pool.mapTx->impl.get<name>().begin();
+    typename indexed_transaction_set::index<name>::type::iterator it = pool.mapTx->impl.get<name>().begin();
     int count = 0;
     for (; it != pool.mapTx->impl.get<name>().end(); ++it, ++count) {
         BOOST_CHECK_EQUAL(it->GetTx().GetHash().ToString(), sortedOrder[count]);
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index fbb4ebbf572486..f8f28b2713341a 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -12,6 +12,7 @@
 #include <consensus/tx_verify.h>
 #include <consensus/validation.h>
 #include <logging.h>
+#include <mempool_set_definitions.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
@@ -34,6 +35,7 @@
 using MemPoolMultiIndex::CompareTxMemPoolEntryByScore;
 using MemPoolMultiIndex::descendant_score;
 using MemPoolMultiIndex::entry_time;
+using MemPoolMultiIndex::indexed_transaction_set;
 using MemPoolMultiIndex::MapTxImpl;
 using MemPoolMultiIndex::raw_setEntries;
 using MemPoolMultiIndex::raw_txiter;
@@ -423,6 +425,8 @@ CTxMemPool::CTxMemPool(const Options& opts)
 {
 }
 
+CTxMemPool::~CTxMemPool() = default;
+
 bool CTxMemPool::isSpent(const COutPoint& outpoint) const
 {
     LOCK(cs);
@@ -679,7 +683,7 @@ namespace {
 class DepthAndScoreComparator
 {
 public:
-    bool operator()(const CTxMemPool::indexed_transaction_set::const_iterator& a, const CTxMemPool::indexed_transaction_set::const_iterator& b)
+    bool operator()(const indexed_transaction_set::const_iterator& a, const indexed_transaction_set::const_iterator& b)
     {
         uint64_t counta = a->GetCountWithAncestors();
         uint64_t countb = b->GetCountWithAncestors();
@@ -691,15 +695,15 @@ class DepthAndScoreComparator
 };
 } // namespace
 
-static std::vector<MemPoolMultiIndex::indexed_transaction_set::const_iterator> GetSortedDepthAndScore(
-    const std::unique_ptr<MemPoolMultiIndex::MapTxImpl>& mapTx, RecursiveMutex& cs) EXCLUSIVE_LOCKS_REQUIRED(cs)
+static std::vector<indexed_transaction_set::const_iterator> GetSortedDepthAndScore(
+    const std::unique_ptr<MapTxImpl>& mapTx, RecursiveMutex& cs) EXCLUSIVE_LOCKS_REQUIRED(cs)
 {
-    std::vector<MemPoolMultiIndex::indexed_transaction_set::const_iterator> iters;
+    std::vector<indexed_transaction_set::const_iterator> iters;
     AssertLockHeld(cs);
 
     iters.reserve(mapTx->impl.size());
 
-    for (MemPoolMultiIndex::indexed_transaction_set::iterator mi = mapTx->impl.begin(); mi != mapTx->impl.end(); ++mi) {
+    for (indexed_transaction_set::iterator mi = mapTx->impl.begin(); mi != mapTx->impl.end(); ++mi) {
         iters.push_back(mi);
     }
     std::sort(iters.begin(), iters.end(), DepthAndScoreComparator());
@@ -844,7 +848,8 @@ void CTxMemPool::queryHashes(std::vector<uint256>& vtxid) const
     }
 }
 
-static TxMempoolInfo GetInfo(CTxMemPool::indexed_transaction_set::const_iterator it) {
+static TxMempoolInfo GetInfo(indexed_transaction_set::const_iterator it)
+{
     return TxMempoolInfo{it->GetSharedTx(), it->GetTime(), it->GetFee(), it->GetTxSize(), it->GetModifiedFee() - it->GetFee()};
 }
 
diff --git a/src/txmempool.h b/src/txmempool.h
index 3e51c0dd409114..a24e7c49e50bf3 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -14,7 +14,6 @@
 #include <kernel/mempool_limits.h>         // IWYU pragma: export
 #include <kernel/mempool_options.h>        // IWYU pragma: export
 #include <kernel/mempool_removal_reason.h> // IWYU pragma: export
-#include <mempool_set_definitions.h>
 #include <policy/feerate.h>
 #include <policy/packages.h>
 #include <primitives/transaction.h>
@@ -34,6 +33,12 @@
 
 class CChain;
 
+namespace MemPoolMultiIndex {
+struct txiter;
+struct MapTxImpl;
+struct setEntries;
+} // namespace MemPoolMultiIndex
+
 /** Fake height value used in Coin to signify they are only in the memory pool (since 0.8) */
 static const uint32_t MEMPOOL_HEIGHT = 0x7FFFFFFF;
 
@@ -197,7 +202,6 @@ class CTxMemPool
      * the mempool is consistent with the new chain tip and fully populated.
      */
 
-    using indexed_transaction_set = MemPoolMultiIndex::indexed_transaction_set;
     using MapTxImpl = MemPoolMultiIndex::MapTxImpl;
 
     mutable RecursiveMutex cs;
@@ -272,6 +276,8 @@ class CTxMemPool
      */
     explicit CTxMemPool(const Options& opts);
 
+    ~CTxMemPool();
+
     /**
      * If sanity-checking is turned on, check makes sure the pool is
      * consistent (does not contain two transactions that spend the same inputs,