diff --git a/closingd/closingd.c b/closingd/closingd.c
index 569c3ed0c..80c10adca 100644
--- a/closingd/closingd.c
+++ b/closingd/closingd.c
@@ -24,6 +24,7 @@
 #include <inttypes.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <wire/common_wiregen.h>
 #include <wire/peer_wire.h>
 #include <wire/wire_sync.h>
 
@@ -113,6 +114,17 @@ static u8 *closing_read_peer_msg(const tal_t *ctx,
 			handle_gossip_msg(pps, take(msg));
 			continue;
 		}
+#if DEVELOPER
+		/* Handle custommsgs */
+		enum peer_wire type = fromwire_peektype(msg);
+		if (type % 2 == 1 && !peer_wire_is_defined(type)) {
+			/* The message is not part of the messages we know
+			 * how to handle. Assume is custommsg, forward it
+			 * to master. */
+			wire_sync_write(REQ_FD, take(towire_custommsg_in(NULL, msg)));
+			continue;
+		}
+#endif
 		if (!handle_peer_gossip_or_error(pps, channel_id, false, msg))
 			return msg;
 	}
diff --git a/lightningd/closing_control.c b/lightningd/closing_control.c
index 813d069fb..2df07d6f5 100644
--- a/lightningd/closing_control.c
+++ b/lightningd/closing_control.c
@@ -19,6 +19,7 @@
 #include <lightningd/options.h>
 #include <lightningd/peer_control.h>
 #include <lightningd/subd.h>
+#include <wire/common_wiregen.h>
 
 static struct amount_sat calc_tx_fee(struct amount_sat sat_in,
 				     const struct bitcoin_tx *tx)
@@ -163,6 +164,19 @@ static unsigned closing_msg(struct subd *sd, const u8 *msg, const int *fds UNUSE
 		break;
 	}
 
+	switch ((enum common_wire)t) {
+#if DEVELOPER
+	case WIRE_CUSTOMMSG_IN:
+		handle_custommsg_in(sd->ld, sd->node_id, msg);
+		break;
+#else
+	case WIRE_CUSTOMMSG_IN:
+#endif
+	/* We send these. */
+	case WIRE_CUSTOMMSG_OUT:
+		break;
+	}
+
 	return 0;
 }