diff --git a/test/functional/p2p_invalid_messages.py b/test/functional/p2p_invalid_messages.py
--- a/test/functional/p2p_invalid_messages.py
+++ b/test/functional/p2p_invalid_messages.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2015-2018 The Bitcoin Core developers
+# Copyright (c) 2015-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test node responses to invalid network messages."""
@@ -144,6 +144,9 @@
 
     def test_magic_bytes(self):
         conn = self.nodes[0].add_p2p_connection(P2PDataStore())
+        # Need to ignore all incoming messages from now, since they come with
+        # "invalid" magic bytes
+        conn._on_data = lambda: None
         conn.magic_bytes = b'\x00\x11\x22\x32'
         with self.nodes[0].assert_debug_log(['PROCESSMESSAGE: INVALID MESSAGESTART ping']):
             conn.send_message(messages.msg_ping(nonce=0xff))