diff --git a/src/test/hash_tests.cpp b/src/test/hash_tests.cpp
index fa9624f13..8be9c580c 100644
--- a/src/test/hash_tests.cpp
+++ b/src/test/hash_tests.cpp
@@ -124,7 +124,11 @@ BOOST_AUTO_TEST_CASE(siphash)
     }
 
     CHashWriter ss(SER_DISK, CLIENT_VERSION);
-    ss << CTransaction();
+    CMutableTransaction tx;
+    // Note these tests were originally written with tx.nVersion=1
+    // and the test would be affected by default tx version bumps if not fixed.
+    tx.nVersion = 1;
+    ss << tx;
     BOOST_CHECK_EQUAL(SipHashUint256(1, 2, ss.GetHash()), 0x79751e980c2a0a35ULL);
 }
 
diff --git a/src/test/txvalidationcache_tests.cpp b/src/test/txvalidationcache_tests.cpp
index 55b4d28fb..9f58f004d 100644
--- a/src/test/txvalidationcache_tests.cpp
+++ b/src/test/txvalidationcache_tests.cpp
@@ -39,6 +39,7 @@ BOOST_FIXTURE_TEST_CASE(tx_mempool_block_doublespend, TestChain100Setup)
     spends.resize(2);
     for (int i = 0; i < 2; i++)
     {
+        spends[i].nVersion = 1;
         spends[i].vin.resize(1);
         spends[i].vin[0].prevout.hash = coinbaseTxns[0].GetHash();
         spends[i].vin[0].prevout.n = 0;