diff --git a/test/functional/abc-p2p-compactblocks.py b/test/functional/abc-p2p-compactblocks.py
--- a/test/functional/abc-p2p-compactblocks.py
+++ b/test/functional/abc-p2p-compactblocks.py
@@ -195,6 +195,7 @@
 
             # Now that we added a bunch of transaction, we need to recompute
             # the merkle root.
+            make_conform_to_ctor(block)
             block.hashMerkleRoot = block.calc_merkle_root()
 
         # Check that the block size is what's expected
@@ -242,6 +243,7 @@
             block = self.blocks[block_number]
             self.add_transactions_to_block(block, new_transactions)
             old_sha256 = block.sha256
+            make_conform_to_ctor(block)
             block.hashMerkleRoot = block.calc_merkle_root()
             block.solve()
             # Update the internal state just like in next_block