diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -28,7 +28,20 @@
 
 #include <memory>
 
-BOOST_FIXTURE_TEST_SUITE(miner_tests, TestingSetup)
+namespace miner_tests {
+struct MinerTestingSetup : public TestingSetup {
+    void TestPackageSelection(const CChainParams &chainparams,
+                              const CScript &scriptPubKey,
+                              const std::vector<CTransactionRef> &txFirst)
+        EXCLUSIVE_LOCKS_REQUIRED(::cs_main, m_node.mempool->cs);
+    bool TestSequenceLocks(const CTransaction &tx, int flags)
+        EXCLUSIVE_LOCKS_REQUIRED(::cs_main, m_node.mempool->cs) {
+        return CheckSequenceLocks(*m_node.mempool, tx, flags);
+    }
+};
+} // namespace miner_tests
+
+BOOST_FIXTURE_TEST_SUITE(miner_tests, MinerTestingSetup)
 
 // BOOST_CHECK_EXCEPTION predicates to check the specific validation error
 class HasReason {
@@ -93,19 +106,12 @@
     return index;
 }
 
-static bool TestSequenceLocks(const CTransaction &tx, int flags)
-    EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
-    LOCK(::g_mempool.cs);
-    return CheckSequenceLocks(::g_mempool, tx, flags);
-}
-
 // Test suite for ancestor feerate transaction selection.
-// Implemented as an additional function, rather than a separate test case, to
-// allow reusing the blockchain created in CreateNewBlock_validity.
-static void TestPackageSelection(const CChainParams &chainparams,
-                                 const CScript &scriptPubKey,
-                                 const std::vector<CTransactionRef> &txFirst)
-    EXCLUSIVE_LOCKS_REQUIRED(cs_main, ::g_mempool.cs) {
+// Implemented as an additional function, rather than a separate test case,
+// to allow reusing the blockchain created in CreateNewBlock_validity.
+void MinerTestingSetup::TestPackageSelection(
+    const CChainParams &chainparams, const CScript &scriptPubKey,
+    const std::vector<CTransactionRef> &txFirst) {
     // Test the ancestor feerate transaction selection.
     TestMemPoolEntryHelper entry;
 
diff --git a/src/test/txvalidationcache_tests.cpp b/src/test/txvalidationcache_tests.cpp
--- a/src/test/txvalidationcache_tests.cpp
+++ b/src/test/txvalidationcache_tests.cpp
@@ -22,16 +22,6 @@
 
 BOOST_AUTO_TEST_SUITE(txvalidationcache_tests)
 
-static bool ToMemPool(const CMutableTransaction &tx) {
-    LOCK(cs_main);
-
-    CValidationState state;
-    return AcceptToMemoryPool(
-        GetConfig(), g_mempool, state, MakeTransactionRef(tx),
-        nullptr /* pfMissingInputs */, true /* bypass_limits */,
-        Amount::zero() /* nAbsurdFee */);
-}
-
 BOOST_FIXTURE_TEST_CASE(tx_mempool_block_doublespend, TestChain100Setup) {
     // Make sure skipping validation of transactions that were validated going
     // into the memory pool does not allow double-spends in blocks to pass
@@ -39,6 +29,16 @@
     CScript scriptPubKey = CScript() << ToByteVector(coinbaseKey.GetPubKey())
                                      << OP_CHECKSIG;
 
+    const auto ToMemPool = [this](const CMutableTransaction &tx) {
+        LOCK(cs_main);
+
+        CValidationState state;
+        return AcceptToMemoryPool(
+            GetConfig(), *m_node.mempool, state, MakeTransactionRef(tx),
+            nullptr /* pfMissingInputs */, true /* bypass_limits */,
+            Amount::zero() /* nAbsurdFee */);
+    };
+
     // Create a double-spend of mature coinbase txn:
     std::vector<CMutableTransaction> spends;
     spends.resize(2);