diff --git a/include/struct.h b/include/struct.h
index 1e3d6b198..092e5c190 100644
--- a/include/struct.h
+++ b/include/struct.h
@@ -2007,6 +2007,8 @@ struct Link {
 	} value;
 };
 
+#define IsInvalidChannelTS(x)	((x) < 750000) /**< Invalid channel creation time */
+
 /**
  * @addtogroup CommonStructs
  * @{
diff --git a/src/modules/channeldb.c b/src/modules/channeldb.c
index 2dcce5d63..83099d5a3 100644
--- a/src/modules/channeldb.c
+++ b/src/modules/channeldb.c
@@ -506,7 +506,10 @@ int read_channeldb(void)
 		R_SAFE(unrealdb_read_str(db, &mode_lock));
 		/* If we got this far, we can create/initialize the channel with the above */
 		channel = make_channel(chname);
-		channel->creationtime = creationtime;
+		if (IsInvalidChannelTS(creationtime))
+			channel->creationtime = TStime();
+		else
+			channel->creationtime = creationtime;
 		safe_strdup(channel->topic, topic);
 		safe_strdup(channel->topic_nick, topic_nick);
 		channel->topic_time = topic_time;
diff --git a/src/modules/mode.c b/src/modules/mode.c
index 9a5168c9d..1160b48d6 100644
--- a/src/modules/mode.c
+++ b/src/modules/mode.c
@@ -417,25 +417,31 @@ void _do_mode(Channel *channel, Client *client, MessageTag *recv_mtags, int parc
 	{
 		if (sendts > 0)
 		{
-			if (!channel->creationtime || sendts < channel->creationtime)
+			if (IsInvalidChannelTS(sendts))
 			{
+				unreal_log(ULOG_WARNING, "mode", "MODE_INVALID_TIMESTAMP", NULL,
+				           "MODE for channel $channel has invalid timestamp $send_timestamp (from $client.name on $client.user.servername)\n"
+				           "Buffer: $modebuf $parabuf",
+				           log_data_channel("channel", channel),
+				           log_data_integer("send_timestamp", sendts),
+				           log_data_string("modebuf", modebuf),
+				           log_data_string("parabuf", parabuf));
+				/* Yeah, so what to do in this case?
+				 * Don't set channel->creationtime
+				 * and assume merging.
+				 */
+				sendts = channel->creationtime;
+			} else
+			if (sendts < channel->creationtime)
+			{
+				/* Our timestamp is wrong (or this is a new channel) */
 				tschange = 1;
 				channel->creationtime = sendts;
-				if (sendts < 750000)
-				{
-					sendto_realops(
-						"Warning! Possible desync: MODE for channel %s ('%s %s') has fishy timestamp (%lld) (from %s/%s)",
-						channel->name, modebuf, parabuf, (long long)sendts, client->direction->name, client->name);
-					ircd_log(LOG_ERROR, "Possible desync: MODE for channel %s ('%s %s') has fishy timestamp (%lld) (from %s/%s)",
-						channel->name, modebuf, parabuf, (long long)sendts, client->direction->name, client->name);
-				}
-				/* new chan or our timestamp is wrong */
-				/* now works for double-bounce prevention */
 
 			}
 			if (sendts > channel->creationtime && channel->creationtime)
 			{
-				/* theirs is wrong but we let it pass anyway */
+				/* Their timestamp is wrong */
 				sendts = channel->creationtime;
 				sendto_one(client, NULL, ":%s MODE %s + %lld", me.name,
 				    channel->name, (long long)channel->creationtime);
diff --git a/src/modules/sjoin.c b/src/modules/sjoin.c
index 7822289b3..6ff4cf2a6 100644
--- a/src/modules/sjoin.c
+++ b/src/modules/sjoin.c
@@ -178,16 +178,25 @@ CMD_FUNC(cmd_sjoin)
 	if (parc < 5)
 		nomode = 1;
 
-	ts = (time_t)atol(parv[1]);
-
 	channel = find_channel(parv[2]);
 	if (!channel)
 	{
 		channel = make_channel(parv[2]);
-		channel->creationtime = ts;
 		oldts = -1;
 	}
 
+	ts = (time_t)atol(parv[1]);
+
+	if (IsInvalidChannelTS(ts))
+	{
+		unreal_log(ULOG_WARNING, "sjoin", "SJOIN_INVALID_TIMESTAMP", NULL,
+			   "SJOIN for channel $channel has invalid timestamp $send_timestamp (from $client)",
+			   log_data_channel("channel", channel),
+			   log_data_integer("send_timestamp", ts));
+		/* Pretend they match our creation time (matches U6 behavior in m_mode.c) */
+		ts = channel->creationtime;
+	}
+
 	if (channel->creationtime > ts)
 	{
 		removeours = 1;
@@ -208,15 +217,6 @@ CMD_FUNC(cmd_sjoin)
 		oldts = channel->creationtime;
 	}
 
-	// FIXME: make it so services cannot screw this up so easily --- if possible...
-	if (ts < 750000)
-	{
-		if (ts != 0)
-			sendto_ops
-			    ("Warning! Possible desync: SJOIN for channel %s has a fishy timestamp (%lld) [%s/%s]",
-			    channel->name, (long long)ts, client->name, client->direction->name);
-	}
-
 	parabuf[0] = '\0';
 	modebuf[0] = '+';
 	modebuf[1] = '\0';