diff --git a/jmbitcoin/jmbitcoin/secp256k1_transaction.py b/jmbitcoin/jmbitcoin/secp256k1_transaction.py
index eb5c5f3..ade53e1 100644
--- a/jmbitcoin/jmbitcoin/secp256k1_transaction.py
+++ b/jmbitcoin/jmbitcoin/secp256k1_transaction.py
@@ -17,7 +17,7 @@ from jmbitcoin.bech32 import *
 P2PKH_PRE, P2PKH_POST = b'\x76\xa9\x14', b'\x88\xac'
 P2SH_P2WPKH_PRE, P2SH_P2WPKH_POST = b'\xa9\x14', b'\x87'
 P2WPKH_PRE = b'\x00\x14'
-P2WSH_PRE = b'\x00\x16'
+P2WSH_PRE = b'\x00\x20'
 
 # Transaction serialization and deserialization
 
@@ -884,4 +884,4 @@ def make_shuffled_tx(ins, outs, deser=True, version=1, locktime=0):
     if deser:
         return deserialize(tx)
     else:
-        return tx
\ No newline at end of file
+        return tx