diff --git a/src/test/DoS_tests.cpp b/src/test/DoS_tests.cpp
--- a/src/test/DoS_tests.cpp
+++ b/src/test/DoS_tests.cpp
@@ -67,12 +67,15 @@
     dummyNode1.fSuccessfullyConnected = true;
 
     // This test requires that we have a chain with non-zero work.
+    LOCK(cs_main);
     BOOST_CHECK(chainActive.Tip() != nullptr);
     BOOST_CHECK(chainActive.Tip()->nChainWork > 0);
 
     // Test starts here
+    LOCK(dummyNode1.cs_sendProcessing);
     // should result in getheaders
     peerLogic->SendMessages(config, &dummyNode1, interruptDummy);
+    LOCK(dummyNode1.cs_vSend);
     BOOST_CHECK(dummyNode1.vSendMsg.size() > 0);
     dummyNode1.vSendMsg.clear();
 
@@ -191,8 +194,12 @@
     peerLogic->InitializeNode(config, &dummyNode1);
     dummyNode1.nVersion = 1;
     dummyNode1.fSuccessfullyConnected = true;
-    // Should get banned.
-    Misbehaving(dummyNode1.GetId(), 100, "");
+    {
+        LOCK(cs_main);
+        // Should get banned.
+        Misbehaving(dummyNode1.GetId(), 100, "");
+    }
+    LOCK(dummyNode1.cs_sendProcessing);
     peerLogic->SendMessages(config, &dummyNode1, interruptDummy);
     BOOST_CHECK(connman->IsBanned(addr1));
     // Different IP, not banned.
@@ -205,13 +212,20 @@
     peerLogic->InitializeNode(config, &dummyNode2);
     dummyNode2.nVersion = 1;
     dummyNode2.fSuccessfullyConnected = true;
-    Misbehaving(dummyNode2.GetId(), 50, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode2.GetId(), 50, "");
+    }
+    LOCK(dummyNode2.cs_sendProcessing);
     peerLogic->SendMessages(config, &dummyNode2, interruptDummy);
     // 2 not banned yet...
     BOOST_CHECK(!connman->IsBanned(addr2));
     // ... but 1 still should be.
     BOOST_CHECK(connman->IsBanned(addr1));
-    Misbehaving(dummyNode2.GetId(), 50, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode2.GetId(), 50, "");
+    }
     peerLogic->SendMessages(config, &dummyNode2, interruptDummy);
     BOOST_CHECK(connman->IsBanned(addr2));
 
@@ -234,13 +248,23 @@
     peerLogic->InitializeNode(config, &dummyNode1);
     dummyNode1.nVersion = 1;
     dummyNode1.fSuccessfullyConnected = true;
-    Misbehaving(dummyNode1.GetId(), 100, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode1.GetId(), 100, "");
+    }
+    LOCK(dummyNode1.cs_sendProcessing);
     peerLogic->SendMessages(config, &dummyNode1, interruptDummy);
     BOOST_CHECK(!connman->IsBanned(addr1));
-    Misbehaving(dummyNode1.GetId(), 10, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode1.GetId(), 10, "");
+    }
     peerLogic->SendMessages(config, &dummyNode1, interruptDummy);
     BOOST_CHECK(!connman->IsBanned(addr1));
-    Misbehaving(dummyNode1.GetId(), 1, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode1.GetId(), 1, "");
+    }
     peerLogic->SendMessages(config, &dummyNode1, interruptDummy);
     BOOST_CHECK(connman->IsBanned(addr1));
     gArgs.ForceSetArg("-banscore", std::to_string(DEFAULT_BANSCORE_THRESHOLD));
@@ -266,7 +290,11 @@
     dummyNode.nVersion = 1;
     dummyNode.fSuccessfullyConnected = true;
 
-    Misbehaving(dummyNode.GetId(), 100, "");
+    {
+        LOCK(cs_main);
+        Misbehaving(dummyNode.GetId(), 100, "");
+    }
+    LOCK(dummyNode.cs_sendProcessing);
     peerLogic->SendMessages(config, &dummyNode, interruptDummy);
     BOOST_CHECK(connman->IsBanned(addr));
 
@@ -282,6 +310,7 @@
 
 CTransactionRef RandomOrphan() {
     std::map<uint256, COrphanTx>::iterator it;
+    LOCK(cs_main);
     it = mapOrphanTransactions.lower_bound(InsecureRand256());
     if (it == mapOrphanTransactions.end()) {
         it = mapOrphanTransactions.begin();
@@ -347,6 +376,7 @@
         BOOST_CHECK(!AddOrphanTx(MakeTransactionRef(tx), i));
     }
 
+    LOCK(cs_main);
     // Test EraseOrphansFor:
     for (NodeId i = 0; i < 3; i++) {
         size_t sizeBefore = mapOrphanTransactions.size();
diff --git a/src/test/blockencodings_tests.cpp b/src/test/blockencodings_tests.cpp
--- a/src/test/blockencodings_tests.cpp
+++ b/src/test/blockencodings_tests.cpp
@@ -65,6 +65,7 @@
     CBlock block(BuildBlockTestCase());
 
     pool.addUnchecked(block.vtx[2]->GetId(), entry.FromTx(*block.vtx[2]));
+    LOCK(pool.cs);
     BOOST_CHECK_EQUAL(
         pool.mapTx.find(block.vtx[2]->GetId())->GetSharedTx().use_count(),
         SHARED_TX_OFFSET + 0);
@@ -175,6 +176,7 @@
     CBlock block(BuildBlockTestCase());
 
     pool.addUnchecked(block.vtx[2]->GetId(), entry.FromTx(*block.vtx[2]));
+    LOCK(pool.cs);
     BOOST_CHECK_EQUAL(
         pool.mapTx.find(block.vtx[2]->GetId())->GetSharedTx().use_count(),
         SHARED_TX_OFFSET + 0);
@@ -256,6 +258,7 @@
     CBlock block(BuildBlockTestCase());
 
     pool.addUnchecked(block.vtx[1]->GetId(), entry.FromTx(*block.vtx[1]));
+    LOCK(pool.cs);
     BOOST_CHECK_EQUAL(
         pool.mapTx.find(block.vtx[1]->GetId())->GetSharedTx().use_count(),
         SHARED_TX_OFFSET + 0);
diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -333,6 +333,7 @@
     sortedOrder[2] = tx1.GetId().ToString(); // 10000
     sortedOrder[3] = tx4.GetId().ToString(); // 15000
     sortedOrder[4] = tx2.GetId().ToString(); // 20000
+    LOCK(pool.cs);
     CheckSort<descendant_score>(pool, sortedOrder, "MempoolIndexingTest1");
 
     /* low fee but with high fee child */
@@ -560,6 +561,7 @@
     }
     sortedOrder[4] = tx3.GetId().ToString(); // 0
 
+    LOCK(pool.cs);
     CheckSort<ancestor_score>(pool, sortedOrder,
                               "MempoolAncestorIndexingTest1");
 
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -183,7 +183,10 @@
 
     // IncrementExtraNonce creates a valid coinbase and merkleRoot
     unsigned int extraNonce = 0;
-    IncrementExtraNonce(config, &block, chainActive.Tip(), extraNonce);
+    {
+        LOCK(cs_main);
+        IncrementExtraNonce(config, &block, chainActive.Tip(), extraNonce);
+    }
 
     while (!CheckProofOfWork(block.GetHash(), block.nBits, config)) {
         ++block.nNonce;
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
@@ -64,6 +64,7 @@
 
     // Test 1: block with both of those transactions should be rejected.
     block = CreateAndProcessBlock(spends, scriptPubKey);
+    LOCK(cs_main);
     BOOST_CHECK(chainActive.Tip()->GetBlockHash() != block.GetHash());
 
     // Test 2: ... and should be rejected if spend1 is in the memory pool
@@ -151,7 +152,10 @@
 BOOST_FIXTURE_TEST_CASE(checkinputs_test, TestChain100Setup) {
     // Test that passing CheckInputs with one set of script flags doesn't imply
     // that we would pass again with a different set of flags.
-    InitScriptExecutionCache();
+    {
+        LOCK(cs_main);
+        InitScriptExecutionCache();
+    }
 
     CScript p2pk_scriptPubKey =
         CScript() << ToByteVector(coinbaseKey.GetPubKey()) << OP_CHECKSIG;
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -594,6 +594,7 @@
         vpwallets[0] = &wallet;
         ::importwallet(GetConfig(), request);
 
+        LOCK(wallet.cs_wallet);
         BOOST_CHECK_EQUAL(wallet.mapWallet.size(), 3);
         BOOST_CHECK_EQUAL(coinbaseTxns.size(), 103);
         for (size_t i = 0; i < coinbaseTxns.size(); ++i) {
@@ -638,6 +639,7 @@
     SetMockTime(mockTime);
     CBlockIndex *block = nullptr;
     if (blockTime > 0) {
+        LOCK(cs_main);
         auto inserted = mapBlockIndex.emplace(GetRandHash(), new CBlockIndex);
         assert(inserted.second);
         const uint256 &hash = inserted.first->first;
@@ -651,6 +653,7 @@
         wtx.SetMerkleBranch(block, 0);
     }
     wallet.AddToWallet(wtx);
+    LOCK(wallet.cs_wallet);
     return wallet.mapWallet.at(wtx.GetId()).nTimeSmart;
 }
 
@@ -685,6 +688,7 @@
 
 BOOST_AUTO_TEST_CASE(LoadReceiveRequests) {
     CTxDestination dest = CKeyID();
+    LOCK(pwalletMain->cs_wallet);
     pwalletMain->AddDestData(dest, "misc", "val_misc");
     pwalletMain->AddDestData(dest, "rr0", "val_rr0");
     pwalletMain->AddDestData(dest, "rr1", "val_rr1");
@@ -727,6 +731,7 @@
                                               changePos, error));
         CValidationState state;
         BOOST_CHECK(wallet->CommitTransaction(wtx, reservekey, nullptr, state));
+        LOCK(wallet->cs_wallet);
         auto it = wallet->mapWallet.find(wtx.GetId());
         BOOST_CHECK(it != wallet->mapWallet.end());
         CreateAndProcessBlock({CMutableTransaction(*it->second.tx)},