diff --git a/nion/swift/command.py b/nion/swift/command.py
index 8c0cb71ec..8ef64b67f 100644
--- a/nion/swift/command.py
+++ b/nion/swift/command.py
@@ -73,22 +73,15 @@ def main() -> None:
 
     success = False
 
-    # next attempt to launch using pyqt
+    # next attempt to launch using pyside6
     try:
-        from PyQt5 import QtCore
-        success = True
-    except ImportError:
-        pass
-
-    # next attempt to launch using pyside2
-    try:
-        from PySide2 import QtCore
+        from PySide6 import QtCore
         success = True
     except ImportError:
         pass
 
     if not success:
-        print("Please install either pyqt or PySide2 using pip or conda or use nionswift-tool to launch.")
+        print("Please install either pyside6 using pip or conda or use nionswift-tool to launch.")
 
     if success:
         app, error = bootstrap_main(sys.argv)
diff --git a/nionswift/__main__.py b/nionswift/__main__.py
index dc6411e15..3874f3dc2 100644
--- a/nionswift/__main__.py
+++ b/nionswift/__main__.py
@@ -2,57 +2,56 @@
 import os
 import subprocess
 import sys
+import typing
 
 parser = argparse.ArgumentParser(
-    prog="python -m nionswift", description="Launch Nion Swift using Qt or a launcher."
+    prog="python -m nionswift", description="Launch Nion Swift using native launcher or pyside6 libraries."
 )
 
 parser.add_argument(
     "--ui",
     dest="ui",
     action="store",
-    choices=["tool", "qt", "pyqt", "pyside2"],
+    choices=["tool", "qt"],
     help="choose UI frontend",
     default="tool",
 )
 
-# python 3.8 compatible
-parser.add_argument('--fallback', action='store_true')
-parser.add_argument('--no-fallback', dest='fallback', action='store_false')
-parser.set_defaults(fallback=True)
-
-# python 3.9+ compatible
-# parser.add_argument(
-#     "--fallback",
-#     dest="fallback",
-#     action=argparse.BooleanOptionalAction,
-#     help="whether to fallback to other UI frontend if preferred choice is unavailable",
-#     default=True,
-# )
+parser.add_argument(
+    "--fallback",
+    dest="fallback",
+    action=argparse.BooleanOptionalAction,
+    help="whether to fall back to other UI frontend if preferred choice is unavailable",
+    default=True,
+)
 
 parsed_args = parser.parse_args()
 
-app = "nionui_app.nionswift"
-args = []
+app_id = "nionui_app.nionswift"
+args = list[typing.Any]()
 
-order = []
+order = list[str]()
 
 if parsed_args.ui:
     order.append(parsed_args.ui)
 
+# if using fallback, add tool and qt to order if not already present.
 if parsed_args.fallback:
     if "tool" not in order:
         order.append("tool")
     if "qt" not in order:
         order.append("qt")
 
+# go through the ui preferences in order
 for ui in order:
     if ui == "qt":
+        # launch the app using the pyside6 qt frontend
         from nionui_app.nionswift import main
-        app = main.main({}, {"pyqt": None})
+        app = main.main(list(), {"qt": None})
         app.run()
         break
     else:
+        # launch using the tool frontend
         if sys.platform == "darwin":
             exe_path = os.path.join(sys.exec_prefix, "bin", "Nion Swift.app", "Contents", "MacOS", "Nion Swift")
         elif sys.platform == "linux":
@@ -63,6 +62,6 @@
             exe_path = None
         if exe_path:
             python_prefix = sys.prefix
-            proc = subprocess.Popen([exe_path, python_prefix, app] + args, universal_newlines=True)
+            proc = subprocess.Popen([exe_path, python_prefix, app_id] + args, universal_newlines=True)
             proc.communicate()
             break
diff --git a/nionui_app/nionswift/main.py b/nionui_app/nionswift/main.py
index 533afed27..6d689af34 100644
--- a/nionui_app/nionswift/main.py
+++ b/nionui_app/nionswift/main.py
@@ -1,10 +1,13 @@
-import os
+import typing
 import warnings
 
-def main(args, bootstrap_args):
-    from nion.swift import Facade
-    from nion.swift import Application
-    from nion.ui import Application as ApplicationUI
+from nion.swift import Application
+from nion.swift import Facade
+from nion.ui import Application as ApplicationUI
+
+
+def main(args: list[typing.Any], bootstrap_args: dict[str, typing.Any]) -> Application.Application:
+    # from nion.swift import Application
     warnings.simplefilter("always", RuntimeWarning)
     Facade.initialize()
     app = Application.Application(ApplicationUI.make_ui(bootstrap_args))