diff --git a/test/functional/p2p_compactblocks.py b/test/functional/p2p_compactblocks.py
index 5a56b8d3b11..ca36b2fbc06 100755
--- a/test/functional/p2p_compactblocks.py
+++ b/test/functional/p2p_compactblocks.py
@@ -733,7 +733,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         # Now send the compact block with all transactions prefilled, and
         # verify that we don't get disconnected.
         comp_block = HeaderAndShortIDs()
-        comp_block.initialize_from_block(block, prefill_list=[0, 1, 2, 3, 4], use_witness=True)
+        comp_block.initialize_from_block(block, prefill_list=list(range(len(block.vtx))), use_witness=True)
         msg = msg_cmpctblock(comp_block.to_p2p())
         test_node.send_and_ping(msg)