diff --git a/src/test/versionbits_tests.cpp b/src/test/versionbits_tests.cpp
index b09827ffe5d..7e96ef923ea 100644
--- a/src/test/versionbits_tests.cpp
+++ b/src/test/versionbits_tests.cpp
@@ -252,38 +252,61 @@ static void check_computeblockversion(const Consensus::Params& params, Consensus
     int64_t nStartTime = params.vDeployments[dep].nStartTime;
     int64_t nTimeout = params.vDeployments[dep].nTimeout;
 
-    assert(nStartTime < nTimeout);
+    // should not be any signalling for first block
+    BOOST_CHECK_EQUAL(ComputeBlockVersion(nullptr, params), VERSIONBITS_TOP_BITS);
+
+    // always active deployments shouldn't need to be tested further
+    if (nStartTime == Consensus::BIP9Deployment::ALWAYS_ACTIVE) return;
+
+    BOOST_REQUIRE(nStartTime < nTimeout);
+    BOOST_REQUIRE(nStartTime >= 0);
+    BOOST_REQUIRE(nTimeout <= std::numeric_limits<uint32_t>::max() || nTimeout == Consensus::BIP9Deployment::NO_TIMEOUT);
+    BOOST_REQUIRE(0 <= bit && bit < 32);
+    BOOST_REQUIRE(((1 << bit) & VERSIONBITS_TOP_MASK) == 0);
 
     // 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;
 
-    // Start generating blocks before nStartTime
-    int64_t nTime = nStartTime - 1;
+    int64_t nTime = nStartTime;
+
+    CBlockIndex *lastBlock = nullptr;
 
     // Before MedianTimePast of the chain has crossed nStartTime, the bit
     // should not be set.
-    CBlockIndex *lastBlock = nullptr;
-    lastBlock = firstChain.Mine(params.nMinerConfirmationWindow, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
-    BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
+    if (nTime == 0) {
+        // since CBlockIndex::nTime is uint32_t we can't represent any
+        // earlier time, so will transition from DEFINED to STARTED at the
+        // end of the first period by mining blocks at nTime == 0
+        lastBlock = firstChain.Mine(params.nMinerConfirmationWindow - 1, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+        BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
+        lastBlock = firstChain.Mine(params.nMinerConfirmationWindow, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+        BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1<<bit)) != 0);
+        // then we'll keep mining at nStartTime...
+    } else {
+        // use a time 1s earlier than start time to check we stay DEFINED
+        --nTime;
 
-    // Mine more blocks (4 less than the adjustment period) at the old time, and check that CBV isn't setting the bit yet.
-    for (uint32_t i = 1; i < params.nMinerConfirmationWindow - 4; i++) {
-        lastBlock = firstChain.Mine(params.nMinerConfirmationWindow + i, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
-        // This works because VERSIONBITS_LAST_OLD_BLOCK_VERSION happens
-        // to be 4, and the bit we're testing happens to be bit 28.
-        BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
-    }
-    // Now mine 5 more blocks at the start time -- MTP should not have passed yet, so
-    // CBV should still not yet set the bit.
-    nTime = nStartTime;
-    for (uint32_t i = params.nMinerConfirmationWindow - 4; i <= params.nMinerConfirmationWindow; i++) {
-        lastBlock = firstChain.Mine(params.nMinerConfirmationWindow + i, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+        // Start generating blocks before nStartTime
+        lastBlock = firstChain.Mine(params.nMinerConfirmationWindow, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
         BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
+
+        // Mine more blocks (4 less than the adjustment period) at the old time, and check that CBV isn't setting the bit yet.
+        for (uint32_t i = 1; i < params.nMinerConfirmationWindow - 4; i++) {
+            lastBlock = firstChain.Mine(params.nMinerConfirmationWindow + i, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+            BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
+        }
+        // Now mine 5 more blocks at the start time -- MTP should not have passed yet, so
+        // CBV should still not yet set the bit.
+        nTime = nStartTime;
+        for (uint32_t i = params.nMinerConfirmationWindow - 4; i <= params.nMinerConfirmationWindow; i++) {
+            lastBlock = firstChain.Mine(params.nMinerConfirmationWindow + i, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+            BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
+        }
+        // Next we will advance to the next period and transition to STARTED,
     }
 
-    // Advance to the next period and transition to STARTED,
     lastBlock = firstChain.Mine(params.nMinerConfirmationWindow * 3, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
     // so ComputeBlockVersion should now set the bit,
     BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1<<bit)) != 0);
@@ -304,17 +327,29 @@ static void check_computeblockversion(const Consensus::Params& params, Consensus
         nHeight += 1;
     }
 
-    nTime = nTimeout;
-    // FAILED is only triggered at the end of a period, so CBV should be setting
-    // the bit until the period transition.
-    for (uint32_t i = 0; i < params.nMinerConfirmationWindow - 1; i++) {
+    if (nTimeout != Consensus::BIP9Deployment::NO_TIMEOUT) {
+        // can reach any nTimeout other than NO_TIMEOUT due to earlier BOOST_REQUIRE
+
+        nTime = nTimeout;
+
+        // finish the last period before we start timing out
+        while (nHeight % params.nMinerConfirmationWindow != 0) {
+            lastBlock = firstChain.Mine(nHeight+1, nTime - 1, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+            BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1<<bit)) != 0);
+            nHeight += 1;
+        }
+
+        // FAILED is only triggered at the end of a period, so CBV should be setting
+        // the bit until the period transition.
+        for (uint32_t i = 0; i < params.nMinerConfirmationWindow - 1; i++) {
+            lastBlock = firstChain.Mine(nHeight+1, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
+            BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1<<bit)) != 0);
+            nHeight += 1;
+        }
+        // The next block should trigger no longer setting the bit.
         lastBlock = firstChain.Mine(nHeight+1, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
-        BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1<<bit)) != 0);
-        nHeight += 1;
+        BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
     }
-    // The next block should trigger no longer setting the bit.
-    lastBlock = firstChain.Mine(nHeight+1, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
-    BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
 
     // On a new chain:
     // verify that the bit will be set after lock-in, and then stop being set
@@ -338,17 +373,18 @@ static void check_computeblockversion(const Consensus::Params& params, Consensus
     BOOST_CHECK((ComputeBlockVersion(lastBlock, params) & (1 << bit)) != 0);
     lastBlock = secondChain.Mine(params.nMinerConfirmationWindow * 3, nTime, VERSIONBITS_LAST_OLD_BLOCK_VERSION).Tip();
     BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, params) & (1<<bit), 0);
-
-    // Finally, verify that after a soft fork has activated, CBV no longer uses
-    // VERSIONBITS_LAST_OLD_BLOCK_VERSION.
-    //BOOST_CHECK_EQUAL(ComputeBlockVersion(lastBlock, mainnetParams) & VERSIONBITS_TOP_MASK, VERSIONBITS_TOP_BITS);
 }
 
 BOOST_AUTO_TEST_CASE(versionbits_computeblockversion)
 {
-    // Use the TESTDUMMY deployment for testing purposes.
-    const auto chainParams = CreateChainParams(*m_node.args, CBaseChainParams::MAIN);
-    check_computeblockversion(chainParams->GetConsensus(), Consensus::DEPLOYMENT_TESTDUMMY);
+    // check that any deployment on any chain can conceivably reach both
+    // ACTIVE and FAILED states in roughly the way we expect
+    for (const auto& chain_name : {CBaseChainParams::MAIN, CBaseChainParams::TESTNET, CBaseChainParams::SIGNET, CBaseChainParams::REGTEST}) {
+        const auto chainParams = CreateChainParams(*m_node.args, chain_name);
+        for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; ++i) {
+            check_computeblockversion(chainParams->GetConsensus(), static_cast<Consensus::DeploymentPos>(i));
+        }
+    }
 }
 
 BOOST_AUTO_TEST_SUITE_END()