diff --git a/contrib/build-wine/deterministic.spec b/contrib/build-wine/deterministic.spec
index c133de4e6..62b471c23 100644
--- a/contrib/build-wine/deterministic.spec
+++ b/contrib/build-wine/deterministic.spec
@@ -62,6 +62,7 @@ a = Analysis([home+'run_electrum',
               home+'electrum/bitcoin.py',
               home+'electrum/dnssec.py',
               home+'electrum/commands.py',
+              home+'electrum/plugins/trustedcoin/qt.py',
               home+'electrum/plugins/cosigner_pool/qt.py',
               home+'electrum/plugins/trezor/qt.py',
               home+'electrum/plugins/safe_t/client.py',
diff --git a/contrib/osx/osx.spec b/contrib/osx/osx.spec
index b4fb53df9..4f3a53acb 100644
--- a/contrib/osx/osx.spec
+++ b/contrib/osx/osx.spec
@@ -67,6 +67,7 @@ a = Analysis([electrum+ MAIN_SCRIPT,
               electrum+'electrum/bitcoin.py',
               electrum+'electrum/dnssec.py',
               electrum+'electrum/commands.py',
+              electrum+'electrum/plugins/trustedcoin/qt.py',
               electrum+'electrum/plugins/cosigner_pool/qt.py',
               electrum+'electrum/plugins/trezor/qt.py',
               electrum+'electrum/plugins/safe_t/client.py',
diff --git a/electrum/gui/common_qt/__init__.py b/electrum/gui/common_qt/__init__.py
index e69de29bb..b2be0c9a4 100644
--- a/electrum/gui/common_qt/__init__.py
+++ b/electrum/gui/common_qt/__init__.py
@@ -0,0 +1,16 @@
+# Copyright (C) 2023 The Electrum developers
+# Distributed under the MIT software license, see the accompanying
+# file LICENCE or http://www.opensource.org/licenses/mit-license.php
+
+import sys
+
+
+# FIXME: remove when both desktop and mobile are Qt6
+def get_qt_major_version() -> int:
+    _GUI_QT_VERSION = getattr(sys, '_GUI_QT_VERSION', None)
+    if _GUI_QT_VERSION is None:
+        # used by pyinstaller when building (analysis phase)
+        _GUI_QT_VERSION = 5
+    if _GUI_QT_VERSION in (5, 6):
+        return _GUI_QT_VERSION
+    raise Exception(f"unexpected {_GUI_QT_VERSION=}")
diff --git a/electrum/gui/common_qt/plugins.py b/electrum/gui/common_qt/plugins.py
index 0934477b4..9edaa9b19 100644
--- a/electrum/gui/common_qt/plugins.py
+++ b/electrum/gui/common_qt/plugins.py
@@ -1,9 +1,13 @@
 import sys
 
-if getattr(sys, '_GUI_QT_VERSION') == 5:  # FIXME: remove when both desktop and mobile are Qt6
+from . import get_qt_major_version
+
+if (qt_ver := get_qt_major_version()) == 5:
     from PyQt5.QtCore import pyqtSignal, pyqtProperty, QObject
-else:
+elif qt_ver == 6:
     from PyQt6.QtCore import pyqtSignal, pyqtProperty, QObject
+else:
+    raise Exception(f"unexpected {qt_ver=}")
 
 from electrum.logging import get_logger
 
diff --git a/electrum/plugins/trustedcoin/common_qt.py b/electrum/plugins/trustedcoin/common_qt.py
index 31b9954e7..01836d972 100644
--- a/electrum/plugins/trustedcoin/common_qt.py
+++ b/electrum/plugins/trustedcoin/common_qt.py
@@ -4,10 +4,14 @@ import base64
 import sys
 from typing import TYPE_CHECKING
 
-if getattr(sys, '_GUI_QT_VERSION') == 5:  # FIXME: remove when both desktop and mobile are Qt6
+from electrum.gui.common_qt import get_qt_major_version
+
+if (qt_ver := get_qt_major_version()) == 5:
     from PyQt5.QtCore import pyqtSignal, pyqtProperty, pyqtSlot
-else:
+elif qt_ver == 6:
     from PyQt6.QtCore import pyqtSignal, pyqtProperty, pyqtSlot
+else:
+    raise Exception(f"unexpected {qt_ver=}")
 
 from electrum.i18n import _
 from electrum.bip32 import BIP32Node