diff --git a/lightningd/channel_control.c b/lightningd/channel_control.c
index 9256151bf..1cb3e84e4 100644
--- a/lightningd/channel_control.c
+++ b/lightningd/channel_control.c
@@ -323,7 +323,7 @@ static unsigned channel_msg(struct subd *sd, const u8 *msg, const int *fds)
 	switch ((enum common_wire_type)t) {
 #if DEVELOPER
 	case WIRE_CUSTOMMSG_IN:
-		/* TODO(cdecker) Add handling of custom messages. */
+		handle_custommsg_in(sd->ld, sd->node_id, msg);
 		break;
 #else
 	case WIRE_CUSTOMMSG_IN:
diff --git a/lightningd/opening_control.c b/lightningd/opening_control.c
index 66eaed5f8..810a45fe5 100644
--- a/lightningd/opening_control.c
+++ b/lightningd/opening_control.c
@@ -926,7 +926,7 @@ static unsigned int openingd_msg(struct subd *openingd,
 	switch ((enum common_wire_type)t) {
 #if DEVELOPER
 	case WIRE_CUSTOMMSG_IN:
-		/* TODO(cdecker) Add handling of custom messages. */
+		handle_custommsg_in(openingd->ld, openingd->node_id, msg);
 		return 0;
 #else
 	case WIRE_CUSTOMMSG_IN:
diff --git a/lightningd/peer_control.c b/lightningd/peer_control.c
index 3de82c74a..bda3ff474 100644
--- a/lightningd/peer_control.c
+++ b/lightningd/peer_control.c
@@ -2375,6 +2375,45 @@ void peer_dev_memleak(struct command *cmd)
 	peer_memleak_req_next(cmd, NULL);
 }
 
+struct custommsg_payload {
+	struct node_id peer_id;
+	const u8 *msg;
+};
+
+static void custommsg_callback(struct custommsg_payload *payload,
+			       const char *buffer, const jsmntok_t *toks)
+{
+	tal_free(payload);
+}
+
+static void custommsg_payload_serialize(struct custommsg_payload *payload,
+					struct json_stream *stream)
+{
+	json_add_hex_talarr(stream, "message", payload->msg);
+	json_add_node_id(stream, "peer_id", &payload->peer_id);
+}
+
+REGISTER_PLUGIN_HOOK(custommsg, custommsg_callback, struct custommsg_payload *,
+		     custommsg_payload_serialize, struct custommsg_payload *);
+
+void handle_custommsg_in(struct lightningd *ld, const struct node_id *peer_id,
+			 const u8 *msg)
+{
+	struct custommsg_payload *p = tal(NULL, struct custommsg_payload);
+	u8 *custommsg;
+
+	if (!fromwire_custommsg_in(NULL, msg, &custommsg)) {
+		log_broken(ld->log, "Malformed custommsg from peer %s: %s",
+			   type_to_string(tmpctx, struct node_id, peer_id),
+			   tal_hex(tmpctx, msg));
+		return;
+	}
+
+	p->peer_id = *peer_id;
+	p->msg = tal_steal(p, custommsg);
+	plugin_hook_call_custommsg(ld, p, p);
+}
+
 static struct command_result *json_sendcustommsg(struct command *cmd,
 						 const char *buffer,
 						 const jsmntok_t *obj UNNEEDED,
diff --git a/lightningd/peer_control.h b/lightningd/peer_control.h
index 100756699..0d53760a9 100644
--- a/lightningd/peer_control.h
+++ b/lightningd/peer_control.h
@@ -93,6 +93,8 @@ struct htlc_in_map *load_channels_from_wallet(struct lightningd *ld);
 
 #if DEVELOPER
 void peer_dev_memleak(struct command *cmd);
+void handle_custommsg_in(struct lightningd *ld, const struct node_id *peer_id,
+			 const u8 *msg);
 #endif /* DEVELOPER */
 
 /* Triggered at each new block.  */
diff --git a/wallet/test/run-wallet.c b/wallet/test/run-wallet.c
index 4c0090a84..b6f5fcbef 100644
--- a/wallet/test/run-wallet.c
+++ b/wallet/test/run-wallet.c
@@ -111,6 +111,9 @@ bool fromwire_channel_sending_commitsig(const tal_t *ctx UNNEEDED, const void *p
 /* Generated stub for fromwire_connect_peer_connected */
 bool fromwire_connect_peer_connected(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct node_id *id UNNEEDED, struct wireaddr_internal *addr UNNEEDED, struct per_peer_state **pps UNNEEDED, u8 **features UNNEEDED)
 { fprintf(stderr, "fromwire_connect_peer_connected called!\n"); abort(); }
+/* Generated stub for fromwire_custommsg_in */
+bool fromwire_custommsg_in(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, u8 **msg UNNEEDED)
+{ fprintf(stderr, "fromwire_custommsg_in called!\n"); abort(); }
 /* Generated stub for fromwire_gossip_get_channel_peer_reply */
 bool fromwire_gossip_get_channel_peer_reply(const tal_t *ctx UNNEEDED, const void *p UNNEEDED, struct node_id **peer_id UNNEEDED)
 { fprintf(stderr, "fromwire_gossip_get_channel_peer_reply called!\n"); abort(); }