diff --git a/hsmd/hsm_wire.csv b/hsmd/hsm_wire.csv
index 5f1a2487f..3914ecb4d 100644
--- a/hsmd/hsm_wire.csv
+++ b/hsmd/hsm_wire.csv
@@ -9,6 +9,7 @@ msgdata,hsmstatus_client_bad_request,msg,u8,len
 # Start the HSM.
 msgtype,hsm_init,11
 msgdata,hsm_init,bip32_key_version,bip32_key_version,
+msgdata,hsm_init,chain_hash,bitcoin_blkid,
 msgdata,hsm_init,dev_force_privkey,?privkey,
 msgdata,hsm_init,dev_force_bip32_seed,?secret,
 msgdata,hsm_init,dev_force_channel_secrets,?secrets,
diff --git a/hsmd/hsmd.c b/hsmd/hsmd.c
index 80def06ca..ac376f6a2 100644
--- a/hsmd/hsmd.c
+++ b/hsmd/hsmd.c
@@ -574,6 +574,7 @@ static struct io_plan *init_hsm(struct io_conn *conn,
 	struct secret *seed;
 	struct secrets *secrets;
 	struct sha256 *shaseed;
+	struct bitcoin_blkid chain_hash;
 
 	/* This must be lightningd. */
 	assert(is_lightningd(c));
@@ -582,7 +583,7 @@ static struct io_plan *init_hsm(struct io_conn *conn,
 	 * definitions in hsm_client_wire.csv.  The format of those files is
 	 * an extension of the simple comma-separated format output by the
 	 * BOLT tools/extract-formats.py tool. */
-	if (!fromwire_hsm_init(NULL, msg_in, &bip32_key_version,
+	if (!fromwire_hsm_init(NULL, msg_in, &bip32_key_version, &chain_hash,
 			       &privkey, &seed, &secrets, &shaseed))
 		return bad_req(conn, c, msg_in);
 
diff --git a/lightningd/hsm_control.c b/lightningd/hsm_control.c
index e7a1d2380..fd90fc90d 100644
--- a/lightningd/hsm_control.c
+++ b/lightningd/hsm_control.c
@@ -80,6 +80,8 @@ void hsm_init(struct lightningd *ld)
 {
 	u8 *msg;
 	int fds[2];
+	struct bitcoin_blkid chainhash;
+	chainhash = get_chainparams(ld)->genesis_blockhash;
 
 	/* We actually send requests synchronously: only status is async. */
 	if (socketpair(AF_LOCAL, SOCK_STREAM, 0, fds) != 0)
@@ -94,7 +96,8 @@ void hsm_init(struct lightningd *ld)
 
 	ld->hsm_fd = fds[0];
 	if (!wire_sync_write(ld->hsm_fd, towire_hsm_init(tmpctx,
-				  &ld->topology->bitcoind->chainparams->bip32_key_version,
+							 &ld->topology->bitcoind->chainparams->bip32_key_version,
+							 &chainhash,
 #if DEVELOPER
 							 ld->dev_force_privkey,
 							 ld->dev_force_bip32_seed,