diff --git a/plugins/cosigner_pool/qt.py b/plugins/cosigner_pool/qt.py
index 524d62b76..e00edd3ba 100644
--- a/plugins/cosigner_pool/qt.py
+++ b/plugins/cosigner_pool/qt.py
@@ -173,7 +173,8 @@ class Plugin(BasePlugin):
         for window, xpub, K, _hash in self.cosigner_list:
             if not self.cosigner_can_sign(tx, xpub):
                 continue
-            message = bitcoin.encrypt_message(bfh(tx.raw), bh2u(K)).decode('ascii')
+            raw_tx_bytes = bfh(str(tx))
+            message = bitcoin.encrypt_message(raw_tx_bytes, bh2u(K)).decode('ascii')
             try:
                 server.put(_hash, message)
             except Exception as e: