diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 85c9cd6934210..2f29b6c362788 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -55,6 +55,9 @@ static CBlock CreateGenesisBlock(uint32_t nTime, uint32_t nNonce, uint32_t nBits
 
 void CChainParams::UpdateVersionBitsParameters(Consensus::DeploymentPos d, int64_t nStartTime, int64_t nTimeout)
 {
+    nStartTime = std::max(nStartTime, -Consensus::BIP9Deployment::MAX_FIXED_HEIGHT);
+    nTimeout = std::min(nTimeout, Consensus::BIP9Deployment::NO_TIMEOUT);
+
     consensus.vDeployments[d].nStartTime = nStartTime;
     consensus.vDeployments[d].nTimeout = nTimeout;
 }
@@ -75,6 +78,7 @@ class CMainParams : public CChainParams {
     CMainParams() {
         strNetworkID = "main";
         consensus.nSubsidyHalvingInterval = 210000;
+        consensus.BIP16Height = 173805; // 00000000000000ce80a7e057163a4db1d5ad7b20fb6f598c9597b9665c8fb0d4 - April 1, 2012
         consensus.BIP34Height = 227931;
         consensus.BIP34Hash = uint256S("0x000000000000024b89b42a942fe0d9fea3bb44ab7bd1b19115dd6a759c0808b8");
         consensus.BIP65Height = 388381; // 000000000000000004c2b624ed5d7756c508d90fd0da2c7c679febfa6c4735f0
@@ -181,6 +185,7 @@ class CTestNetParams : public CChainParams {
     CTestNetParams() {
         strNetworkID = "test";
         consensus.nSubsidyHalvingInterval = 210000;
+        consensus.BIP16Height = 514; // 00000000040b4e986385315e14bee30ad876d8b47f748025b26683116d21aa65
         consensus.BIP34Height = 21111;
         consensus.BIP34Hash = uint256S("0x0000000023b3a96d3484e5abb3755c413e7d41500f8e2a5c3f0dd01299cd8ef8");
         consensus.BIP65Height = 581885; // 00000000007f6655f22f98e72ed80d8b06dc761d5da09df0fa1dc4be4f861eb6
@@ -271,6 +276,7 @@ class CRegTestParams : public CChainParams {
     CRegTestParams() {
         strNetworkID = "regtest";
         consensus.nSubsidyHalvingInterval = 150;
+        consensus.BIP16Height = 0; // always enforce P2SH BIP16 on regtest
         consensus.BIP34Height = 100000000; // BIP34 has not activated on regtest (far in the future so block v1 are not rejected in tests)
         consensus.BIP34Hash = uint256();
         consensus.BIP65Height = 1351; // BIP65 activated on regtest (Used in rpc activation tests)
@@ -284,13 +290,13 @@ class CRegTestParams : public CChainParams {
         consensus.nMinerConfirmationWindow = 144; // Faster than normal for regtest (144 instead of 2016)
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].bit = 28;
         consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nStartTime = 0;
-        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = 999999999999ULL;
+        consensus.vDeployments[Consensus::DEPLOYMENT_TESTDUMMY].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
         consensus.vDeployments[Consensus::DEPLOYMENT_CSV].bit = 0;
         consensus.vDeployments[Consensus::DEPLOYMENT_CSV].nStartTime = 0;
-        consensus.vDeployments[Consensus::DEPLOYMENT_CSV].nTimeout = 999999999999ULL;
+        consensus.vDeployments[Consensus::DEPLOYMENT_CSV].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
         consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].bit = 1;
-        consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nStartTime = 0;
-        consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 999999999999ULL;
+        consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nStartTime = -1; // Always on
+        consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = Consensus::BIP9Deployment::NO_TIMEOUT;
 
         // The best chain should have at least this much work.
         consensus.nMinimumChainWork = uint256S("0x00");
diff --git a/src/consensus/params.h b/src/consensus/params.h
index 6240e82857eb9..227191d20a97c 100644
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -27,18 +27,24 @@ enum DeploymentPos
 struct BIP9Deployment {
     /** Bit position to select the particular bit in nVersion. */
     int bit;
-    /** Start MedianTime for version bits miner confirmation. Can be a date in the past */
+    /** Start MedianTime for version bits miner confirmation. Can be a date in the past. Negative numbers mean hardcoded height. */
     int64_t nStartTime;
     /** Timeout/expiry MedianTime for the deployment attempt. */
     int64_t nTimeout;
+
+    static const int64_t NO_TIMEOUT = 999999999999ULL;
+    static const int64_t MAX_FIXED_HEIGHT = 4294967296LL;
 };
 
+
 /**
  * Parameters that influence chain consensus.
  */
 struct Params {
     uint256 hashGenesisBlock;
     int nSubsidyHalvingInterval;
+    /** Block height at which BIP16 becomes active */
+    int BIP16Height;
     /** Block height and hash at which BIP34 becomes active */
     int BIP34Height;
     uint256 BIP34Hash;
diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
index 41e0626eb9011..2851808cf4a5e 100644
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -335,23 +335,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     BOOST_CHECK_THROW(AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey), std::runtime_error);
     mempool.clear();
 
-    // invalid (pre-p2sh) txn in mempool, template creation fails
-    tx.vin[0].prevout.hash = txFirst[0]->GetHash();
-    tx.vin[0].prevout.n = 0;
-    tx.vin[0].scriptSig = CScript() << OP_1;
-    tx.vout[0].nValue = BLOCKSUBSIDY-LOWFEE;
-    script = CScript() << OP_0;
-    tx.vout[0].scriptPubKey = GetScriptForDestination(CScriptID(script));
-    hash = tx.GetHash();
-    mempool.addUnchecked(hash, entry.Fee(LOWFEE).Time(GetTime()).SpendsCoinbase(true).FromTx(tx));
-    tx.vin[0].prevout.hash = hash;
-    tx.vin[0].scriptSig = CScript() << std::vector<unsigned char>(script.begin(), script.end());
-    tx.vout[0].nValue -= LOWFEE;
-    hash = tx.GetHash();
-    mempool.addUnchecked(hash, entry.Fee(LOWFEE).Time(GetTime()).SpendsCoinbase(false).FromTx(tx));
-    BOOST_CHECK_THROW(AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey), std::runtime_error);
-    mempool.clear();
-
     // double spend txn pair in mempool, template creation fails
     tx.vin[0].prevout.hash = txFirst[0]->GetHash();
     tx.vin[0].scriptSig = CScript() << OP_1;
@@ -391,6 +374,24 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         chainActive.SetTip(next);
     }
     BOOST_CHECK(pblocktemplate = AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey));
+
+    // invalid p2sh txn in mempool, template creation fails
+    tx.vin[0].prevout.hash = txFirst[0]->GetHash();
+    tx.vin[0].prevout.n = 0;
+    tx.vin[0].scriptSig = CScript() << OP_1;
+    tx.vout[0].nValue = BLOCKSUBSIDY-LOWFEE;
+    script = CScript() << OP_0;
+    tx.vout[0].scriptPubKey = GetScriptForDestination(CScriptID(script));
+    hash = tx.GetHash();
+    mempool.addUnchecked(hash, entry.Fee(LOWFEE).Time(GetTime()).SpendsCoinbase(true).FromTx(tx));
+    tx.vin[0].prevout.hash = hash;
+    tx.vin[0].scriptSig = CScript() << std::vector<unsigned char>(script.begin(), script.end());
+    tx.vout[0].nValue -= LOWFEE;
+    hash = tx.GetHash();
+    mempool.addUnchecked(hash, entry.Fee(LOWFEE).Time(GetTime()).SpendsCoinbase(false).FromTx(tx));
+    BOOST_CHECK_THROW(AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey), std::runtime_error);
+    mempool.clear();
+
     // Delete the dummy blocks again.
     while (chainActive.Tip()->nHeight > nHeight) {
         CBlockIndex* del = chainActive.Tip();
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
index 79bc48a118094..4230a7e12d6a0 100644
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -106,6 +106,7 @@ TestingSetup::~TestingSetup()
 
 TestChain100Setup::TestChain100Setup() : TestingSetup(CBaseChainParams::REGTEST)
 {
+    UpdateVersionBitsParameters(Consensus::DEPLOYMENT_SEGWIT, 0, 999999999999ULL);
     // Generate a 100-block chain:
     coinbaseKey.MakeNewKey(true);
     CScript scriptPubKey = CScript() <<  ToByteVector(coinbaseKey.GetPubKey()) << OP_CHECKSIG;
diff --git a/src/test/versionbits_tests.cpp b/src/test/versionbits_tests.cpp
index 882afb2e20341..6eb86ea3d44ba 100644
--- a/src/test/versionbits_tests.cpp
+++ b/src/test/versionbits_tests.cpp
@@ -32,6 +32,16 @@ class TestConditionChecker : public AbstractThresholdConditionChecker
     int GetStateSinceHeightFor(const CBlockIndex* pindexPrev) const { return AbstractThresholdConditionChecker::GetStateSinceHeightFor(pindexPrev, paramsDummy, cache); }
 };
 
+class TestFixedHeightConditionChecker : public TestConditionChecker
+{
+public:
+    const static int Never = 9999999;
+    int activation_height;
+    int64_t BeginTime(const Consensus::Params& params) const override { return -activation_height; }
+    TestFixedHeightConditionChecker(int height) : activation_height(height) { }
+    TestFixedHeightConditionChecker() : activation_height(Never) { }
+};
+
 #define CHECKERS 6
 
 class VersionBitsTester
@@ -43,26 +53,33 @@ class VersionBitsTester
     // The first one performs all checks, the second only 50%, the third only 25%, etc...
     // This is to test whether lack of cached information leads to the same results.
     TestConditionChecker checker[CHECKERS];
+    // Another 6 that assume fixed height activation
+    TestFixedHeightConditionChecker checker_fixed[CHECKERS];
 
     // Test counter (to identify failures)
     int num;
 
 public:
-    VersionBitsTester() : num(0) {}
+    VersionBitsTester(int height) : num(0) {
+        for (unsigned int  i = 0; i < CHECKERS; i++) {
+            checker_fixed[i] = TestFixedHeightConditionChecker(height);
+        }
+    }
 
-    VersionBitsTester& Reset() {
+    VersionBitsTester& Reset(int height) {
         for (unsigned int i = 0; i < vpblock.size(); i++) {
             delete vpblock[i];
         }
         for (unsigned int  i = 0; i < CHECKERS; i++) {
             checker[i] = TestConditionChecker();
+            checker_fixed[i] = TestFixedHeightConditionChecker(height);
         }
         vpblock.clear();
         return *this;
     }
 
     ~VersionBitsTester() {
-         Reset();
+         Reset(TestFixedHeightConditionChecker::Never);
     }
 
     VersionBitsTester& Mine(unsigned int height, int32_t nTime, int32_t nVersion) {
@@ -81,7 +98,9 @@ class VersionBitsTester
     VersionBitsTester& TestStateSinceHeight(int height) {
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
+                const int height_fixed = (checker_fixed[i].activation_height <= height ? height : 0);
                 BOOST_CHECK_MESSAGE(checker[i].GetStateSinceHeightFor(vpblock.empty() ? nullptr : vpblock.back()) == height, strprintf("Test %i for StateSinceHeight", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateSinceHeightFor(vpblock.empty() ? nullptr : vpblock.back()) == height_fixed, strprintf("Test %i for StateSinceHeight (fixed height)", num));
             }
         }
         num++;
@@ -92,6 +111,7 @@ class VersionBitsTester
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
                 BOOST_CHECK_MESSAGE(checker[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_DEFINED, strprintf("Test %i for DEFINED", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_DEFINED, strprintf("Test %i for DEFINED (fixed height)", num));
             }
         }
         num++;
@@ -102,6 +122,7 @@ class VersionBitsTester
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
                 BOOST_CHECK_MESSAGE(checker[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_STARTED, strprintf("Test %i for STARTED", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_DEFINED, strprintf("Test %i for STARTED (fixed height)", num));
             }
         }
         num++;
@@ -112,6 +133,7 @@ class VersionBitsTester
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
                 BOOST_CHECK_MESSAGE(checker[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_LOCKED_IN, strprintf("Test %i for LOCKED_IN", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_DEFINED, strprintf("Test %i for LOCKED_IN (fixed height)", num));
             }
         }
         num++;
@@ -122,6 +144,7 @@ class VersionBitsTester
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
                 BOOST_CHECK_MESSAGE(checker[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_ACTIVE, strprintf("Test %i for ACTIVE", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_ACTIVE, strprintf("Test %i for ACTIVE (fixed height)", num));
             }
         }
         num++;
@@ -132,6 +155,7 @@ class VersionBitsTester
         for (int i = 0; i < CHECKERS; i++) {
             if (InsecureRandBits(i) == 0) {
                 BOOST_CHECK_MESSAGE(checker[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_FAILED, strprintf("Test %i for FAILED", num));
+                BOOST_CHECK_MESSAGE(checker_fixed[i].GetStateFor(vpblock.empty() ? nullptr : vpblock.back()) == THRESHOLD_DEFINED, strprintf("Test %i for FAILED (fixed height)", num));
             }
         }
         num++;
@@ -147,7 +171,7 @@ BOOST_AUTO_TEST_CASE(versionbits_test)
 {
     for (int i = 0; i < 64; i++) {
         // DEFINED -> FAILED
-        VersionBitsTester().TestDefined().TestStateSinceHeight(0)
+        VersionBitsTester(TestFixedHeightConditionChecker::Never).TestDefined().TestStateSinceHeight(0)
                            .Mine(1, TestTime(1), 0x100).TestDefined().TestStateSinceHeight(0)
                            .Mine(11, TestTime(11), 0x100).TestDefined().TestStateSinceHeight(0)
                            .Mine(989, TestTime(989), 0x100).TestDefined().TestStateSinceHeight(0)
@@ -160,9 +184,9 @@ BOOST_AUTO_TEST_CASE(versionbits_test)
                            .Mine(3000, TestTime(30005), 0x100).TestFailed().TestStateSinceHeight(1000)
 
         // DEFINED -> STARTED -> FAILED
-                           .Reset().TestDefined().TestStateSinceHeight(0)
+                           .Reset(TestFixedHeightConditionChecker::Never).TestDefined().TestStateSinceHeight(0)
                            .Mine(1, TestTime(1), 0).TestDefined().TestStateSinceHeight(0)
-                           .Mine(1000, TestTime(10000) - 1, 0x100).TestDefined().TestStateSinceHeight(0) // One second more and it would be defined
+                           .Mine(1000, TestTime(10000) - 1, 0x100).TestDefined().TestStateSinceHeight(0) // One second more and it would be started
                            .Mine(2000, TestTime(10000), 0x100).TestStarted().TestStateSinceHeight(2000) // So that's what happens the next period
                            .Mine(2051, TestTime(10010), 0).TestStarted().TestStateSinceHeight(2000) // 51 old blocks
                            .Mine(2950, TestTime(10020), 0x100).TestStarted().TestStateSinceHeight(2000) // 899 new blocks
@@ -170,9 +194,9 @@ BOOST_AUTO_TEST_CASE(versionbits_test)
                            .Mine(4000, TestTime(20010), 0x100).TestFailed().TestStateSinceHeight(3000)
 
         // DEFINED -> STARTED -> FAILED while threshold reached
-                           .Reset().TestDefined().TestStateSinceHeight(0)
+                           .Reset(TestFixedHeightConditionChecker::Never).TestDefined().TestStateSinceHeight(0)
                            .Mine(1, TestTime(1), 0).TestDefined().TestStateSinceHeight(0)
-                           .Mine(1000, TestTime(10000) - 1, 0x101).TestDefined().TestStateSinceHeight(0) // One second more and it would be defined
+                           .Mine(1000, TestTime(10000) - 1, 0x101).TestDefined().TestStateSinceHeight(0) // One second more and it would be started
                            .Mine(2000, TestTime(10000), 0x101).TestStarted().TestStateSinceHeight(2000) // So that's what happens the next period
                            .Mine(2999, TestTime(30000), 0x100).TestStarted().TestStateSinceHeight(2000) // 999 new blocks
                            .Mine(3000, TestTime(30000), 0x100).TestFailed().TestStateSinceHeight(3000) // 1 new block (so 1000 out of the past 1000 are new)
@@ -182,9 +206,9 @@ BOOST_AUTO_TEST_CASE(versionbits_test)
                            .Mine(24000, TestTime(40000), 0).TestFailed().TestStateSinceHeight(3000)
 
         // DEFINED -> STARTED -> LOCKEDIN at the last minute -> ACTIVE
-                           .Reset().TestDefined()
+                           .Reset(4000).TestDefined()
                            .Mine(1, TestTime(1), 0).TestDefined().TestStateSinceHeight(0)
-                           .Mine(1000, TestTime(10000) - 1, 0x101).TestDefined().TestStateSinceHeight(0) // One second more and it would be defined
+                           .Mine(1000, TestTime(10000) - 1, 0x101).TestDefined().TestStateSinceHeight(0) // One second more and it would be started
                            .Mine(2000, TestTime(10000), 0x101).TestStarted().TestStateSinceHeight(2000) // So that's what happens the next period
                            .Mine(2050, TestTime(10010), 0x200).TestStarted().TestStateSinceHeight(2000) // 50 old blocks
                            .Mine(2950, TestTime(10020), 0x100).TestStarted().TestStateSinceHeight(2000) // 900 new blocks
@@ -196,7 +220,7 @@ BOOST_AUTO_TEST_CASE(versionbits_test)
                            .Mine(24000, TestTime(40000), 0).TestActive().TestStateSinceHeight(4000)
 
         // DEFINED multiple periods -> STARTED multiple periods -> FAILED
-                           .Reset().TestDefined().TestStateSinceHeight(0)
+                           .Reset(TestFixedHeightConditionChecker::Never).TestDefined().TestStateSinceHeight(0)
                            .Mine(999, TestTime(999), 0).TestDefined().TestStateSinceHeight(0)
                            .Mine(1000, TestTime(1000), 0).TestDefined().TestStateSinceHeight(0)
                            .Mine(2000, TestTime(2000), 0).TestDefined().TestStateSinceHeight(0)
@@ -248,7 +272,7 @@ BOOST_AUTO_TEST_CASE(versionbits_computeblockversion)
     // In the first chain, test that the bit is set by CBV until it has failed.
     // In the second chain, test the bit is set by CBV while STARTED and
     // LOCKED-IN, and then no longer set while ACTIVE.
-    VersionBitsTester firstChain, secondChain;
+    VersionBitsTester firstChain(6048), secondChain(6048);
 
     // Start generating blocks before nStartTime
     int64_t nTime = nStartTime - 1;
diff --git a/src/validation.cpp b/src/validation.cpp
index 7f6697c780080..d8f77bf55eeb5 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1587,11 +1587,12 @@ static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS];
 static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& consensusparams) {
     AssertLockHeld(cs_main);
 
-    // BIP16 didn't become active until Apr 1 2012
-    int64_t nBIP16SwitchTime = 1333238400;
-    bool fStrictPayToScriptHash = (pindex->GetBlockTime() >= nBIP16SwitchTime);
+    unsigned int flags = SCRIPT_VERIFY_NONE;
 
-    unsigned int flags = fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE;
+    // Start enforcing P2SH (BIP16)
+    if (pindex->nHeight >= consensusparams.BIP16Height) {
+        flags |= SCRIPT_VERIFY_P2SH;
+    }
 
     // Start enforcing the DERSIG (BIP66) rule
     if (pindex->nHeight >= consensusparams.BIP66Height) {
diff --git a/src/versionbits.cpp b/src/versionbits.cpp
index 64ae9396724ad..638a827e09547 100644
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -27,6 +27,12 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
     int64_t nTimeStart = BeginTime(params);
     int64_t nTimeTimeout = EndTime(params);
 
+    // Check if this deployment has a fixed activation height.
+    if (nTimeStart < 0) {
+        if (pindexPrev && pindexPrev->nHeight + 1 >= -nTimeStart) return THRESHOLD_ACTIVE;
+        return THRESHOLD_DEFINED;
+    }
+
     // A block's state is always the same as that of the first of its period, so it is computed based on a pindexPrev whose height equals a multiple of nPeriod - 1.
     if (pindexPrev != nullptr) {
         pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - ((pindexPrev->nHeight + 1) % nPeriod));
@@ -136,6 +142,12 @@ BIP9Stats AbstractThresholdConditionChecker::GetStateStatisticsFor(const CBlockI
 
 int AbstractThresholdConditionChecker::GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const
 {
+    int64_t start_time = BeginTime(params);
+    if (start_time < 0) {
+        if (pindexPrev && pindexPrev->nHeight + 1 >= -start_time) return -start_time;
+        return 0;
+    }
+
     const ThresholdState initialState = GetStateFor(pindexPrev, params, cache);
 
     // BIP 9 about state DEFINED: "The genesis block is by definition in this state for each deployment."
diff --git a/test/functional/nulldummy.py b/test/functional/nulldummy.py
index 91c4550653826..a70fc31970554 100755
--- a/test/functional/nulldummy.py
+++ b/test/functional/nulldummy.py
@@ -40,7 +40,9 @@ class NULLDUMMYTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
         self.setup_clean_chain = True
-        self.extra_args = [['-whitelist=127.0.0.1', '-walletprematurewitness']]
+        # This scripts tests NULLDUMMY activation, which is part of the 'segwit' deployment, so we set segwit
+        # to be initially inactive here.
+        self.extra_args = [['-whitelist=127.0.0.1', '-walletprematurewitness', '-vbparams=segwit:0:999999999999']]
 
     def run_test(self):
         self.address = self.nodes[0].getnewaddress()
diff --git a/test/functional/p2p-compactblocks.py b/test/functional/p2p-compactblocks.py
index 94513d3f4387b..3a5ce3acf21ee 100755
--- a/test/functional/p2p-compactblocks.py
+++ b/test/functional/p2p-compactblocks.py
@@ -93,7 +93,7 @@ def set_test_params(self):
         self.setup_clean_chain = True
         # Node0 = pre-segwit, node1 = segwit-aware
         self.num_nodes = 2
-        self.extra_args = [["-vbparams=segwit:0:0"], ["-txindex"]]
+        self.extra_args = [["-vbparams=segwit:0:0"], ["-vbparams=segwit:0:999999999999", "-txindex"]]
         self.utxos = []
 
     def build_block_on_tip(self, node, segwit=False):
diff --git a/test/functional/p2p-segwit.py b/test/functional/p2p-segwit.py
index a9ef47559b6bc..e19838c938a8f 100755
--- a/test/functional/p2p-segwit.py
+++ b/test/functional/p2p-segwit.py
@@ -111,7 +111,7 @@ class SegWitTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 3
-        self.extra_args = [["-whitelist=127.0.0.1"], ["-whitelist=127.0.0.1", "-acceptnonstdtxn=0"], ["-whitelist=127.0.0.1", "-vbparams=segwit:0:0"]]
+        self.extra_args = [["-whitelist=127.0.0.1", "-vbparams=segwit:0:999999999999"], ["-whitelist=127.0.0.1", "-acceptnonstdtxn=0", "-vbparams=segwit:0:999999999999"], ["-whitelist=127.0.0.1", "-vbparams=segwit:0:0"]]
 
     def setup_network(self):
         self.setup_nodes()
@@ -1493,7 +1493,7 @@ def test_upgrade_after_activation(self, node_id):
 
         # Restart with the new binary
         self.stop_node(node_id)
-        self.start_node(node_id, extra_args=[])
+        self.start_node(node_id, extra_args=["-vbparams=segwit:0:999999999999"])
         connect_nodes(self.nodes[0], node_id)
 
         sync_blocks(self.nodes)
diff --git a/test/functional/segwit.py b/test/functional/segwit.py
index 6ecade7cb6a4c..0117b4be3617e 100755
--- a/test/functional/segwit.py
+++ b/test/functional/segwit.py
@@ -77,9 +77,9 @@ class SegWitTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 3
-        self.extra_args = [["-walletprematurewitness", "-rpcserialversion=0"],
-                           ["-blockversion=4", "-promiscuousmempoolflags=517", "-prematurewitness", "-walletprematurewitness", "-rpcserialversion=1"],
-                           ["-blockversion=536870915", "-promiscuousmempoolflags=517", "-prematurewitness", "-walletprematurewitness"]]
+        self.extra_args = [["-walletprematurewitness", "-rpcserialversion=0", "-vbparams=segwit:0:999999999999"],
+                           ["-blockversion=4", "-promiscuousmempoolflags=517", "-prematurewitness", "-walletprematurewitness", "-rpcserialversion=1", "-vbparams=segwit:0:999999999999"],
+                           ["-blockversion=536870915", "-promiscuousmempoolflags=517", "-prematurewitness", "-walletprematurewitness", "-vbparams=segwit:0:999999999999"]]
 
     def setup_network(self):
         super().setup_network()
diff --git a/test/functional/sendheaders.py b/test/functional/sendheaders.py
index fe577dc20a2db..23a74a5f53ae3 100755
--- a/test/functional/sendheaders.py
+++ b/test/functional/sendheaders.py
@@ -215,7 +215,7 @@ def run_test(self):
         connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], inv_node))
         # Set nServices to 0 for test_node, so no block download will occur outside of
         # direct fetching
-        connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], test_node, services=0))
+        connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], test_node, services=NODE_WITNESS))
         inv_node.add_connection(connections[0])
         test_node.add_connection(connections[1])
 
diff --git a/test/functional/test_framework/blockstore.py b/test/functional/test_framework/blockstore.py
index 4b2170a03f28d..a1d4d1ff79e32 100644
--- a/test/functional/test_framework/blockstore.py
+++ b/test/functional/test_framework/blockstore.py
@@ -100,7 +100,7 @@ def add_header(self, header):
     def get_blocks(self, inv):
         responses = []
         for i in inv:
-            if (i.type == 2): # MSG_BLOCK
+            if (i.type == 2 or i.type == (2 | (1 << 30))): # MSG_BLOCK or MSG_WITNESS_BLOCK
                 data = self.get(i.hash)
                 if data is not None:
                     # Use msg_generic to avoid re-serialization
@@ -153,7 +153,7 @@ def add_transaction(self, tx):
     def get_transactions(self, inv):
         responses = []
         for i in inv:
-            if (i.type == 1): # MSG_TX
+            if (i.type == 1 or i.type == (1 | (1 << 30))): # MSG_TX or MSG_WITNESS_TX
                 tx = self.get(i.hash)
                 if tx is not None:
                     responses.append(msg_generic(b"tx", tx))
diff --git a/test/functional/test_framework/comptool.py b/test/functional/test_framework/comptool.py
index bfbc0c3b03409..5d51613d1a3e1 100755
--- a/test/functional/test_framework/comptool.py
+++ b/test/functional/test_framework/comptool.py
@@ -80,9 +80,9 @@ def on_getdata(self, conn, message):
         [conn.send_message(r) for r in self.tx_store.get_transactions(message.inv)]
 
         for i in message.inv:
-            if i.type == 1:
+            if i.type == 1 or i.type == 1 | (1 << 30): # MSG_TX or MSG_WITNESS_TX
                 self.tx_request_map[i.hash] = True
-            elif i.type == 2:
+            elif i.type == 2 or i.type == 2 | (1 << 30): # MSG_BLOCK or MSG_WITNESS_BLOCK
                 self.block_request_map[i.hash] = True
 
     def on_inv(self, conn, message):
diff --git a/test/functional/test_framework/mininode.py b/test/functional/test_framework/mininode.py
index c6f596156a777..2d7a27ef67e50 100755
--- a/test/functional/test_framework/mininode.py
+++ b/test/functional/test_framework/mininode.py
@@ -949,7 +949,7 @@ class msg_version(object):
 
     def __init__(self):
         self.nVersion = MY_VERSION
-        self.nServices = 1
+        self.nServices = NODE_NETWORK | NODE_WITNESS
         self.nTime = int(time.time())
         self.addrTo = CAddress()
         self.addrFrom = CAddress()
@@ -1650,7 +1650,7 @@ class NodeConn(asyncore.dispatcher):
         "regtest": b"\xfa\xbf\xb5\xda",   # regtest
     }
 
-    def __init__(self, dstaddr, dstport, rpc, callback, net="regtest", services=NODE_NETWORK, send_version=True):
+    def __init__(self, dstaddr, dstport, rpc, callback, net="regtest", services=NODE_NETWORK|NODE_WITNESS, send_version=True):
         asyncore.dispatcher.__init__(self, map=mininode_socket_map)
         self.dstaddr = dstaddr
         self.dstport = dstport
diff --git a/test/functional/zmq_test.py b/test/functional/zmq_test.py
index 382ef5bae2891..311e8606054d7 100755
--- a/test/functional/zmq_test.py
+++ b/test/functional/zmq_test.py
@@ -8,6 +8,7 @@
 import struct
 
 from test_framework.test_framework import BitcoinTestFramework, SkipTest
+from test_framework.mininode import CTransaction, BytesIO
 from test_framework.util import (assert_equal,
                                  bytes_to_hex_str,
                                  hash256,
@@ -71,12 +72,14 @@ def _zmq_test(self):
         msg = self.zmqSubSocket.recv_multipart()
         topic = msg[0]
         assert_equal(topic, b"rawtx")
-        body = msg[1]
+        body = CTransaction()
+        body.deserialize(BytesIO(msg[1]))
+        body.calc_sha256()
         msgSequence = struct.unpack('<I', msg[-1])[-1]
         assert_equal(msgSequence, 0) # must be sequence 0 on rawtx
 
         # Check that the rawtx hashes to the hashtx
-        assert_equal(hash256(body), txhash)
+        assert_equal(body.hash, bytes_to_hex_str(txhash))
 
         self.log.info("Wait for block")
         msg = self.zmqSubSocket.recv_multipart()
@@ -127,6 +130,7 @@ def _zmq_test(self):
 
         self.log.info("Wait for tx from second node")
         # test tx from a second node
+        self.sync_all()
         hashRPC = self.nodes[1].sendtoaddress(self.nodes[0].getnewaddress(), 1.0)
         self.sync_all()