diff --git a/tests/test_closing.py b/tests/test_closing.py
index d4c678b1caf0..a6f2e9b4156f 100644
--- a/tests/test_closing.py
+++ b/tests/test_closing.py
@@ -2526,10 +2526,11 @@ def test_onchain_middleman_fulfill_after_fail(node_factory, bitcoind):
     l3.daemon.wait_for_log(' to ONCHAIN')
 
     # Now l3 learns the preimage, and spends what it's owed.
+    # Both HTLCs get a success tx; they share a wallet UTXO for fee boost
+    # so only one can enter the mempool at a time. Mine whichever gets in.
     l3.rpc.releasehtlc(preimage)
-    _, txid, _ = l3.wait_for_onchaind_tx('OUR_HTLC_SUCCESS_TX',
-                                         'OUR_UNILATERAL/THEIR_HTLC')
-    bitcoind.generate_block(1, wait_for_mempool=[txid])
+    l3.daemon.wait_for_logs(['Telling lightningd about OUR_HTLC_SUCCESS_TX to resolve OUR_UNILATERAL/THEIR_HTLC'] * 2)
+    bitcoind.generate_block(1, wait_for_mempool=1)
     l2.daemon.wait_for_log('THEIR_UNILATERAL/OUR_HTLC gave us preimage')
 
     # Both payments must succeed, including the one l3 said it failed.