diff --git a/tests/blockchain/test_blockchain.py b/tests/blockchain/test_blockchain.py
index 7075f6fc47da..55ff0e2228c4 100644
--- a/tests/blockchain/test_blockchain.py
+++ b/tests/blockchain/test_blockchain.py
@@ -1503,10 +1503,10 @@ class TestBlockHeaderValidation:
             # the test constants set MAX_FUTURE_TIME to 10 days, restore it to
             # default for this test
             constants = bt.constants.replace(SOFT_FORK2_HEIGHT=0, MAX_FUTURE_TIME=5 * 60)
-            time_delta = 2 * 60
+            time_delta = 2 * 60 + 1
         else:
             constants = bt.constants.replace(MAX_FUTURE_TIME=5 * 60)
-            time_delta = 5 * 60
+            time_delta = 5 * 60 + 1
 
         blocks = bt.get_consecutive_blocks(1)