diff --git a/bitcoin/block.c b/bitcoin/block.c
index 6838f2c39344..076d443f8915 100644
--- a/bitcoin/block.c
+++ b/bitcoin/block.c
@@ -155,7 +155,7 @@ bitcoin_block_from_hex(const tal_t *ctx, const struct chainparams *chainparams,
 
 	/* De-hex the array. */
 	len = hex_data_size(hexlen);
-	p = linear_tx = tal_arr(ctx, u8, len);
+	p = linear_tx = tal_arr(b, u8, len);
 	if (!hex_decode(hex, hexlen, linear_tx, len))
 		return tal_free(b);
 
@@ -210,6 +210,8 @@ bitcoin_block_from_hex(const tal_t *ctx, const struct chainparams *chainparams,
 	b->txids = tal_arr(b, struct bitcoin_txid, num);
 	for (i = 0; i < num; i++) {
 		b->tx[i] = pull_bitcoin_tx_only(b->tx, &p, &len);
+		if (!b->tx[i])
+			return tal_free(b);
 		b->tx[i]->chainparams = chainparams;
 		bitcoin_txid(b->tx[i], &b->txids[i]);
 	}
diff --git a/bitcoin/test/run-bitcoin_block_from_hex.c b/bitcoin/test/run-bitcoin_block_from_hex.c
index 94b26ad5d05f..aa1bf7c99b23 100644
--- a/bitcoin/test/run-bitcoin_block_from_hex.c
+++ b/bitcoin/test/run-bitcoin_block_from_hex.c
@@ -68,6 +68,7 @@ int main(int argc, const char *argv[])
 	struct sha256_double merkle;
 	struct bitcoin_txid txid, expected_txid;
 	struct bitcoin_block *b;
+	size_t blocklen;
 
 	common_setup(argv[0]);
 	chainparams = chainparams_for_network("bitcoin");
@@ -103,6 +104,12 @@ int main(int argc, const char *argv[])
 	assert(bitcoin_txid_eq(&txid, &expected_txid));
 
 	tal_free(b);
+
+	/* Every truncation of a valid block must be refused, not crash. */
+	blocklen = strlen(block);
+	for (size_t i = 1; i < blocklen; i++)
+		assert(!bitcoin_block_from_hex(NULL, chainparams, block, i));
+
 	common_shutdown();
 	return 0;
 }