diff --git a/tests/test_gossip.py b/tests/test_gossip.py
index a0f37c84f..c7753e4d2 100644
--- a/tests/test_gossip.py
+++ b/tests/test_gossip.py
@@ -39,7 +39,9 @@ def test_gossip_pruning(node_factory, bitcoind):
     scid2, _ = l2.fundchannel(l3, 10**6)
 
     mine_funding_to_announce(bitcoind, [l1, l2, l3])
+    l1_initial_cupdate_timestamp = only_one(l1.rpc.listchannels(source=l1.info['id'])['channels'])['last_update']
 
+    # Get timestamps of initial updates, so we can ensure they change.
     # Channels should be activated locally
     wait_for(lambda: [c['active'] for c in l1.rpc.listchannels()['channels']] == [True] * 4)
     wait_for(lambda: [c['active'] for c in l2.rpc.listchannels()['channels']] == [True] * 4)
@@ -57,6 +59,10 @@ def test_gossip_pruning(node_factory, bitcoind):
         'Sending keepalive channel_update for {}'.format(scid2),
     ])
 
+    # Everyone should see l1's update change.
+    for n in (l1, l2, l3):
+        wait_for(lambda: only_one(n.rpc.listchannels(source=l1.info['id'])['channels'])['last_update'] != l1_initial_cupdate_timestamp)
+
     # Now kill l2, so that l1 and l3 will prune from their view after 60 seconds
     l2.stop()