diff --git a/bitcoin/tx.c b/bitcoin/tx.c
index 6be607b74d18..f6fb836de084 100644
--- a/bitcoin/tx.c
+++ b/bitcoin/tx.c
@@ -443,14 +443,19 @@ u8 *linearize_wtx(const tal_t *ctx, const struct wally_tx *wtx)
 	return arr;
 }
 
-size_t bitcoin_tx_weight(const struct bitcoin_tx *tx)
+size_t wally_tx_weight(const struct wally_tx *wtx)
 {
 	size_t weight;
-	int ret = wally_tx_get_weight(tx->wtx, &weight);
+	int ret = wally_tx_get_weight(wtx, &weight);
 	assert(ret == WALLY_OK);
 	return weight;
 }
 
+size_t bitcoin_tx_weight(const struct bitcoin_tx *tx)
+{
+	return wally_tx_weight(tx->wtx);
+}
+
 void wally_txid(const struct wally_tx *wtx, struct bitcoin_txid *txid)
 {
 	u8 *arr;
diff --git a/bitcoin/tx.h b/bitcoin/tx.h
index 40d7f6969412..3ebac3f4ae17 100644
--- a/bitcoin/tx.h
+++ b/bitcoin/tx.h
@@ -59,6 +59,7 @@ u8 *linearize_wtx(const tal_t *ctx, const struct wally_tx *wtx);
 
 /* Get weight of tx in Sipa. */
 size_t bitcoin_tx_weight(const struct bitcoin_tx *tx);
+size_t wally_tx_weight(const struct wally_tx *wtx);
 
 /* Allocate a tx: you just need to fill in inputs and outputs (they're
  * zeroed with inputs' sequence_number set to FFFFFFFF) */