diff --git a/test/functional/p2p_compactblocks.py b/test/functional/p2p_compactblocks.py
index 1990b9d3d..d77a74475 100755
--- a/test/functional/p2p_compactblocks.py
+++ b/test/functional/p2p_compactblocks.py
@@ -10,7 +10,7 @@ Version 2 compact blocks are post-segwit (wtxids)
 import random
 
 from test_framework.blocktools import create_block, create_coinbase, add_witness_commitment
-from test_framework.messages import BlockTransactions, BlockTransactionsRequest, calculate_shortid, CBlock, CBlockHeader, CInv, COutPoint, CTransaction, CTxIn, CTxInWitness, CTxOut, FromHex, HeaderAndShortIDs, msg_no_witness_block, msg_no_witness_blocktxn, msg_cmpctblock, msg_getblocktxn, msg_getdata, msg_getheaders, msg_headers, msg_inv, msg_sendcmpct, msg_sendheaders, msg_tx, msg_block, msg_blocktxn, MSG_BLOCK, MSG_WITNESS_FLAG, NODE_NETWORK, P2PHeaderAndShortIDs, PrefilledTransaction, ser_uint256, ToHex
+from test_framework.messages import BlockTransactions, BlockTransactionsRequest, calculate_shortid, CBlock, CBlockHeader, CInv, COutPoint, CTransaction, CTxIn, CTxInWitness, CTxOut, FromHex, HeaderAndShortIDs, msg_no_witness_block, msg_no_witness_blocktxn, msg_cmpctblock, msg_getblocktxn, msg_getdata, msg_getheaders, msg_headers, msg_inv, msg_sendcmpct, msg_sendheaders, msg_tx, msg_block, msg_blocktxn, MSG_BLOCK, MSG_CMPCT_BLOCK, MSG_WITNESS_FLAG, NODE_NETWORK, P2PHeaderAndShortIDs, PrefilledTransaction, ser_uint256, ToHex
 from test_framework.mininode import mininode_lock, P2PInterface
 from test_framework.script import CScript, OP_TRUE, OP_DROP
 from test_framework.test_framework import BitcoinTestFramework
@@ -307,7 +307,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         # Now fetch the compact block using a normal non-announce getdata
         with mininode_lock:
             test_node.clear_block_announcement()
-            inv = CInv(4, block_hash)  # 4 == "CompactBlock"
+            inv = CInv(MSG_CMPCT_BLOCK, block_hash)
             test_node.send_message(msg_getdata([inv]))
 
         wait_until(test_node.received_block_announcement, timeout=30, lock=mininode_lock)
@@ -634,7 +634,7 @@ class CompactBlocksTest(BitcoinTestFramework):
             wait_until(test_node.received_block_announcement, timeout=30, lock=mininode_lock)
 
         test_node.clear_block_announcement()
-        test_node.send_message(msg_getdata([CInv(4, int(new_blocks[0], 16))]))
+        test_node.send_message(msg_getdata([CInv(MSG_CMPCT_BLOCK, int(new_blocks[0], 16))]))
         wait_until(lambda: "cmpctblock" in test_node.last_message, timeout=30, lock=mininode_lock)
 
         test_node.clear_block_announcement()
@@ -643,7 +643,7 @@ class CompactBlocksTest(BitcoinTestFramework):
         test_node.clear_block_announcement()
         with mininode_lock:
             test_node.last_message.pop("block", None)
-        test_node.send_message(msg_getdata([CInv(4, int(new_blocks[0], 16))]))
+        test_node.send_message(msg_getdata([CInv(MSG_CMPCT_BLOCK, int(new_blocks[0], 16))]))
         wait_until(lambda: "block" in test_node.last_message, timeout=30, lock=mininode_lock)
         with mininode_lock:
             test_node.last_message["block"].block.calc_sha256()
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index 4855f62a8..f97fb89c2 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -54,6 +54,7 @@ NODE_NETWORK_LIMITED = (1 << 10)
 MSG_TX = 1
 MSG_BLOCK = 2
 MSG_FILTERED_BLOCK = 3
+MSG_CMPCT_BLOCK = 4
 MSG_WITNESS_FLAG = 1 << 30
 MSG_TYPE_MASK = 0xffffffff >> 2