diff --git a/devtools/Makefile b/devtools/Makefile
index 0fd8f625a..5166b9e7c 100644
--- a/devtools/Makefile
+++ b/devtools/Makefile
@@ -1,6 +1,6 @@
 DEVTOOLS_SRC := devtools/gen_print_wire.c devtools/gen_print_onion_wire.c devtools/print_wire.c
 DEVTOOLS_OBJS := $(DEVTOOLS_SRC:.c=.o)
-DEVTOOLS := devtools/bolt11-cli devtools/decodemsg devtools/onion devtools/dump-gossipstore devtools/gossipwith devtools/create-gossipstore devtools/mkcommit devtools/mkfunding devtools/mkclose devtools/mkgossip devtools/mkencoded
+DEVTOOLS := devtools/bolt11-cli devtools/decodemsg devtools/onion devtools/dump-gossipstore devtools/gossipwith devtools/create-gossipstore devtools/mkcommit devtools/mkfunding devtools/mkclose devtools/mkgossip devtools/mkencoded devtools/checkchannels
 DEVTOOLS_TOOL_SRC := $(DEVTOOLS:=.c)
 DEVTOOLS_TOOL_OBJS := $(DEVTOOLS_TOOL_SRC:.c=.o)
 
@@ -76,6 +76,8 @@ devtools/mkgossip: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/fro
 
 devtools/mkencoded: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) wire/fromwire.o wire/towire.o wire/tlvstream.o devtools/mkencoded.o
 
+devtools/checkchannels: $(DEVTOOLS_COMMON_OBJS) $(CCAN_OBJS) $(BITCOIN_OBJS) common/configdir.o wire/fromwire.o wire/towire.o wire/tlvstream.o devtools/checkchannels.o
+
 # Make sure these depend on everything.
 ALL_PROGRAMS += $(DEVTOOLS)
 ALL_OBJS += $(DEVTOOLS_OBJS) $(DEVTOOLS_TOOL_OBJS)
diff --git a/devtools/checkchannels.c b/devtools/checkchannels.c
new file mode 100644
index 000000000..93e5ec65b
--- /dev/null
+++ b/devtools/checkchannels.c
@@ -0,0 +1,239 @@
+#include "config.h"
+#include <assert.h>
+#include <bitcoin/privkey.h>
+#include <bitcoin/script.h>
+#include <bitcoin/short_channel_id.h>
+#include <bitcoin/tx.h>
+#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
+#include <ccan/err/err.h>
+#include <ccan/mem/mem.h>
+#include <ccan/opt/opt.h>
+#include <ccan/tal/grab_file/grab_file.h>
+#include <ccan/tal/path/path.h>
+#include <common/configdir.h>
+#include <common/node_id.h>
+#include <common/utils.h>
+#include <inttypes.h>
+#include <sqlite3.h>
+
+static void hsm_channel_secret_base(struct secret *channel_seed_base,
+				    const struct secret *hsm_secret)
+{
+	hkdf_sha256(channel_seed_base, sizeof(struct secret), NULL, 0,
+		    hsm_secret, sizeof(*hsm_secret),
+		    /*~ Initially, we didn't support multiple channels per
+		     * peer at all: a channel had to be completely forgotten
+		     * before another could exist.  That was slightly relaxed,
+		     * but the phrase "peer seed" is wired into the seed
+		     * generation here, so we need to keep it that way for
+		     * existing clients, rather than using "channel seed". */
+		    "peer seed", strlen("peer seed"));
+}
+
+static void get_channel_seed(const struct secret *hsm_secret,
+			     const struct node_id *peer_id, u64 dbid,
+			     struct secret *channel_seed)
+{
+	struct secret channel_base;
+	u8 input[sizeof(peer_id->k) + sizeof(dbid)];
+	/*~ Again, "per-peer" should be "per-channel", but Hysterical Raisins */
+	const char *info = "per-peer seed";
+
+	/*~ We use the DER encoding of the pubkey, because it's platform
+	 * independent.  Since the dbid is unique, however, it's completely
+	 * unnecessary, but again, existing users can't be broken. */
+	/* FIXME: lnd has a nicer BIP32 method for deriving secrets which we
+	 * should migrate to. */
+	hsm_channel_secret_base(&channel_base, hsm_secret);
+	memcpy(input, peer_id->k, sizeof(peer_id->k));
+	BUILD_ASSERT(sizeof(peer_id->k) == PUBKEY_CMPR_LEN);
+	/*~ For all that talk about platform-independence, note that this
+	 * field is endian-dependent!  But let's face it, little-endian won.
+	 * In related news, we don't support EBCDIC or middle-endian. */
+	memcpy(input + PUBKEY_CMPR_LEN, &dbid, sizeof(dbid));
+
+	hkdf_sha256(channel_seed, sizeof(*channel_seed),
+		    input, sizeof(input),
+		    &channel_base, sizeof(channel_base),
+		    info, strlen(info));
+}
+
+struct keys {
+	struct privkey f, r, h, p, d;
+	struct sha256 shaseed;
+};
+
+static void derive_keys(const struct secret *seed, struct keys *keys)
+{
+	hkdf_sha256(keys, sizeof(*keys), NULL, 0, seed, sizeof(*seed),
+		    "c-lightning", strlen("c-lightning"));
+}
+
+static void derive_funding_key(const struct secret *hsm_secret,
+			       const struct node_id *peer_id, u64 dbid,
+			       struct pubkey *funding_pubkey)
+{
+	struct secret channel_seed;
+	struct keys keys;
+
+	get_channel_seed(hsm_secret, peer_id, dbid, &channel_seed);
+	derive_keys(&channel_seed, &keys);
+
+	if (!pubkey_from_privkey(&keys.f, funding_pubkey))
+		abort();
+}
+
+static void sqlite3_column_pubkey(struct sqlite3_stmt *stmt, int pos, struct pubkey *dest)
+{
+	bool ok;
+	assert(sqlite3_column_bytes(stmt, pos) == PUBKEY_CMPR_LEN);
+	ok = pubkey_from_der(sqlite3_column_blob(stmt, pos), PUBKEY_CMPR_LEN, dest);
+	assert(ok);
+}
+
+static void sqlite3_column_short_channel_id(struct sqlite3_stmt *stmt,
+					    int pos,
+					    struct short_channel_id *dest)
+{
+	const char *source = sqlite3_column_blob(stmt, pos);
+	size_t sourcelen = sqlite3_column_bytes(stmt, pos);
+	if (!short_channel_id_from_str(source, sourcelen, dest))
+		abort();
+}
+
+static void copy_column(void *dst, size_t size,
+			struct sqlite3_stmt *stmt,
+			int pos)
+{
+	assert(sqlite3_column_bytes(stmt, pos) == size);
+	memcpy(dst, sqlite3_column_blob(stmt, pos), size);
+}
+
+int main(int argc, char *argv[])
+{
+	char *config_dir, *hsmfile, *dbfile;
+	sqlite3 *sql;
+	sqlite3_stmt *stmt;
+	int flags = SQLITE_OPEN_READONLY, dberr;
+	struct secret *hsm_secret;
+	bool verbose = false;
+	size_t num, num_ok;
+
+	setup_locale();
+	wally_init(0);
+	secp256k1_ctx = wally_get_secp_context();
+
+	config_dir = default_configdir(NULL);
+	opt_register_arg("--lightning-dir=<dir>",
+			 opt_set_talstr, opt_show_charp,
+			 &config_dir,
+			 "Where to find hsm_secret and lightningd.sqlite3");
+	opt_register_noarg("-v|--verbose", opt_set_bool, &verbose,
+			 "Print everything");
+
+	opt_parse(&argc, argv, opt_log_stderr_exit);
+	if (argc != 1)
+		errx(1, "no arguments accepted");
+
+	hsmfile = path_join(config_dir, config_dir, "hsm_secret");
+	dbfile = path_join(config_dir, config_dir, "lightningd.sqlite3");
+
+	dberr = sqlite3_open_v2(dbfile, &sql, flags, NULL);
+	if (dberr != SQLITE_OK)
+		errx(1, "failed to open database %s: %s", dbfile,
+			 sqlite3_errstr(dberr));
+
+	hsm_secret = grab_file(hsmfile, hsmfile);
+	if (!hsm_secret)
+		err(1, "failed to read %s", hsmfile);
+
+	dberr = sqlite3_prepare_v2(sql,
+				   "SELECT channels.id, peers.node_id, channels.short_channel_id, channels.funding_tx_id, channels.funding_tx_outnum, channels.funding_satoshi, channels.fundingkey_remote, utxoset.scriptpubkey, utxoset.satoshis FROM channels INNER JOIN peers ON channels.peer_id = peers.id LEFT JOIN utxoset on channels.funding_tx_id = utxoset.txid AND channels.funding_tx_outnum = utxoset.outnum;", -1, &stmt, NULL); /* Raw: false positive! */
+	if (dberr != SQLITE_OK)
+		errx(1, "failed to prepare query for %s: %s", dbfile,
+			 sqlite3_errstr(dberr));
+
+	num = num_ok = 0;
+	while ((dberr = sqlite3_step(stmt)) == SQLITE_ROW) {
+		u64 dbid;
+		struct node_id peer_id;
+		struct short_channel_id scid;
+		struct bitcoin_txid funding_txid;
+		u32 funding_outnum;
+		u64 funding_satoshis;
+		struct pubkey remote_fundingkey, local_fundingkey;
+		u8 *scriptpubkey;
+		u64 utxo_satoshis;
+		const tal_t *ctx = tal(dbfile, char);
+		char txid_hex[65];
+		u8 *wscript, *expect_scriptpubkey;
+
+		num++;
+
+		dbid = sqlite3_column_int64(stmt, 0);
+		copy_column(&peer_id, sizeof(peer_id), stmt, 1);
+		sqlite3_column_short_channel_id(stmt, 2, &scid);
+		copy_column(&funding_txid, sizeof(funding_txid), stmt, 3);
+		if (!bitcoin_txid_to_hex(&funding_txid,
+					 txid_hex, sizeof(txid_hex)))
+			abort();
+		funding_outnum = sqlite3_column_int(stmt, 4);
+		funding_satoshis = sqlite3_column_int64(stmt, 5);
+		sqlite3_column_pubkey(stmt, 6, &remote_fundingkey);
+
+		printf("Channel %s with peer %s: funding %s/%u: ",
+			     short_channel_id_to_str(ctx, &scid),
+			     node_id_to_hexstr(ctx, &peer_id),
+			     txid_hex, funding_outnum);
+		fflush(stdout);
+
+		/* UTXO DNE */
+		if (sqlite3_column_type(stmt, 7) == SQLITE_NULL) {
+			printf("*** FATAL *** unknown funding output\n");
+			continue;
+		}
+
+		scriptpubkey = tal_dup_arr(ctx, u8,
+					   sqlite3_column_blob(stmt, 7),
+					   sqlite3_column_bytes(stmt, 7), 0);
+		utxo_satoshis = sqlite3_column_int64(stmt, 8);
+
+		derive_funding_key(hsm_secret, &peer_id, dbid,
+				   &local_fundingkey);
+
+		wscript = bitcoin_redeem_2of2(ctx, &local_fundingkey, &remote_fundingkey);
+		expect_scriptpubkey = scriptpubkey_p2wsh(ctx, wscript);
+
+		if (!memeq(expect_scriptpubkey, tal_bytelen(expect_scriptpubkey),
+			   scriptpubkey, tal_bytelen(scriptpubkey))) {
+			printf("*** FATAL *** outscript %s should be %s\n",
+			       tal_hex(ctx, scriptpubkey),
+			       tal_hex(ctx, expect_scriptpubkey));
+			continue;
+		}
+
+		if (utxo_satoshis != funding_satoshis) {
+			printf("*** FATAL *** amount %"PRIu64" should be %"PRIu64,
+			       funding_satoshis, utxo_satoshis);
+			continue;
+		}
+		if (verbose)
+			printf("scriptpubkey = %s, expected %s,"
+			       " amount = %"PRIu64", expected %"PRIu64": ",
+			       tal_hex(ctx, scriptpubkey),
+			       tal_hex(ctx, expect_scriptpubkey),
+			       funding_satoshis, utxo_satoshis);
+		printf("OK\n");
+		num_ok++;
+		tal_free(ctx);
+	}
+	if (dberr != SQLITE_DONE)
+		errx(1, "failed iterating database: %s",
+		     sqlite3_errstr(dberr));
+
+	if (num_ok == num)
+		printf("\nCheck passed!\n");
+	else
+		errx(1, "%zu channels incorrect.", num - num_ok);
+	tal_free(config_dir);
+}