diff --git a/lightningd/peer_control.c b/lightningd/peer_control.c
index 284dc78bb..0b817c5e5 100644
--- a/lightningd/peer_control.c
+++ b/lightningd/peer_control.c
@@ -1437,15 +1437,16 @@ static bool check_funding_details(const struct bitcoin_tx *tx,
 				  struct amount_sat funding,
 				  u32 funding_outnum)
 {
-	struct amount_asset asset =
-	    bitcoin_tx_output_get_amount(tx, funding_outnum);
-
-	if (!amount_asset_is_main(&asset))
-		return false;
+	struct amount_asset asset;
 
 	if (funding_outnum >= tx->wtx->num_outputs)
 		return false;
 
+	asset = bitcoin_tx_output_get_amount(tx, funding_outnum);
+
+	if (!amount_asset_is_main(&asset))
+		return false;
+
 	if (!amount_sat_eq(amount_asset_to_sat(&asset), funding))
 		return false;