diff --git a/src/gtest/test_pow.cpp b/src/gtest/test_pow.cpp
index 4557f6db1..b0dd5fa41 100644
--- a/src/gtest/test_pow.cpp
+++ b/src/gtest/test_pow.cpp
@@ -16,7 +16,7 @@ TEST(PoW, DifficultyAveraging) {
     for (int i = 0; i <= lastBlk; i++) {
         blocks[i].pprev = i ? &blocks[i - 1] : nullptr;
         blocks[i].nHeight = i;
-        blocks[i].nTime = 1269211443 + i * params.nPowTargetSpacing;
+        blocks[i].nTime = 1269211443 + i * params.PoWTargetSpacing(blocks[i].nHeight);
         blocks[i].nBits = 0x1e7fffff; /* target 0x007fffff000... */
         blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
     }
@@ -32,12 +32,12 @@ TEST(PoW, DifficultyAveraging) {
     // Result should be unchanged, modulo integer division precision loss
     arith_uint256 bnRes;
     bnRes.SetCompact(0x1e7fffff);
-    bnRes /= params.AveragingWindowTimespan();
-    bnRes *= params.AveragingWindowTimespan();
+    bnRes /= params.AveragingWindowTimespan(blocks[lastBlk].nHeight);
+    bnRes *= params.AveragingWindowTimespan(blocks[lastBlk].nHeight);
     EXPECT_EQ(bnRes.GetCompact(), GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
 
     // Randomise the final block time (plus 1 to ensure it is always different)
-    blocks[lastBlk].nTime += GetRand(params.nPowTargetSpacing/2) + 1;
+    blocks[lastBlk].nTime += GetRand(params.PoWTargetSpacing(blocks[lastBlk].nHeight)/2) + 1;
 
     // Result should be the same as if last difficulty was used
     bnAvg.SetCompact(blocks[lastBlk].nBits);
@@ -80,24 +80,24 @@ TEST(PoW, MinDifficultyRules) {
     for (int i = 0; i <= lastBlk; i++) {
         blocks[i].pprev = i ? &blocks[i - 1] : nullptr;
         blocks[i].nHeight = params.nPowAllowMinDifficultyBlocksAfterHeight.get() + i;
-        blocks[i].nTime = 1269211443 + i * params.nPowTargetSpacing;
+        blocks[i].nTime = 1269211443 + i * params.PoWTargetSpacing(blocks[i].nHeight);
         blocks[i].nBits = 0x1e7fffff; /* target 0x007fffff000... */
         blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
     }
 
     // Create a new block at the target spacing
     CBlockHeader next;
-    next.nTime = blocks[lastBlk].nTime + params.nPowTargetSpacing;
+    next.nTime = blocks[lastBlk].nTime + params.PoWTargetSpacing(blocks[lastBlk].nHeight + 1);
 
     // Result should be unchanged, modulo integer division precision loss
     arith_uint256 bnRes;
     bnRes.SetCompact(0x1e7fffff);
-    bnRes /= params.AveragingWindowTimespan();
-    bnRes *= params.AveragingWindowTimespan();
+    bnRes /= params.AveragingWindowTimespan(blocks[lastBlk].nHeight);
+    bnRes *= params.AveragingWindowTimespan(blocks[lastBlk].nHeight);
     EXPECT_EQ(GetNextWorkRequired(&blocks[lastBlk], &next, params), bnRes.GetCompact());
 
     // Delay last block up to the edge of the min-difficulty limit
-    next.nTime += params.nPowTargetSpacing * 5;
+    next.nTime += params.PoWTargetSpacing(blocks[lastBlk].nHeight + 1) * 5;
 
     // Result should be unchanged, modulo integer division precision loss
     EXPECT_EQ(GetNextWorkRequired(&blocks[lastBlk], &next, params), bnRes.GetCompact());
diff --git a/src/test/alert_tests.cpp b/src/test/alert_tests.cpp
index 18acf1f67..f50f7c497 100644
--- a/src/test/alert_tests.cpp
+++ b/src/test/alert_tests.cpp
@@ -391,7 +391,7 @@ BOOST_AUTO_TEST_CASE(PartitionAlert)
     CCriticalSection csDummy;
     CBlockIndex indexDummy[400];
     CChainParams& params = Params(CBaseChainParams::MAIN);
-    int64_t nPowTargetSpacing = params.GetConsensus().nPowTargetSpacing;
+    int64_t nPowTargetSpacing = params.GetConsensus().PoWTargetSpacing(0); // First 400 blocks are pre-Blossom
 
     // Generate fake blockchain timestamps relative to
     // an arbitrary time:
diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
index 23e7634ab..11bcaa060 100644
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -168,7 +168,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
         // of the next block must be six spacings ahead of that to be at least
         // one spacing ahead of the tip. Within 11 blocks of genesis, the median
         // will be closer to the tip, and blocks will appear slower.
-        pblock->nTime = chainActive.Tip()->GetMedianTimePast()+6*Params().GetConsensus().nPowTargetSpacing;
+        pblock->nTime = chainActive.Tip()->GetMedianTimePast()+6*Params().GetConsensus().PoWTargetSpacing(i);
         CMutableTransaction txCoinbase(pblock->vtx[0]);
         txCoinbase.nVersion = 1;
         txCoinbase.vin[0].scriptSig = CScript() << (chainActive.Height()+1) << OP_0;
diff --git a/src/test/pow_tests.cpp b/src/test/pow_tests.cpp
index 5a11483f2..a83f5914b 100644
--- a/src/test/pow_tests.cpp
+++ b/src/test/pow_tests.cpp
@@ -78,7 +78,7 @@ BOOST_AUTO_TEST_CASE(GetBlockProofEquivalentTime_test)
     for (int i = 0; i < 10000; i++) {
         blocks[i].pprev = i ? &blocks[i - 1] : NULL;
         blocks[i].nHeight = i;
-        blocks[i].nTime = 1269211443 + i * params.nPowTargetSpacing;
+        blocks[i].nTime = 1269211443 + i * params.PoWTargetSpacing(blocks[i].nHeight);
         blocks[i].nBits = 0x207fffff; /* target 0x7fffff000... */
         blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
     }