diff --git a/plugins/trezor/qt_generic.py b/plugins/trezor/qt_generic.py
index 9aadd42f..9b855078 100644
--- a/plugins/trezor/qt_generic.py
+++ b/plugins/trezor/qt_generic.py
@@ -401,6 +401,7 @@ class SettingsDialog(WindowModalDialog):
             invoke_client('set_pin', remove=True)
 
         def wipe_device():
+            wallet = window.wallet
             if wallet and sum(wallet.get_balance()):
                 title = _("Confirm Device Wipe")
                 msg = _("Are you SURE you want to wipe the device?\n"