diff --git a/dangerzone/isolation_provider/qubes.py b/dangerzone/isolation_provider/qubes.py
index 2f99e892..4fd8f49d 100644
--- a/dangerzone/isolation_provider/qubes.py
+++ b/dangerzone/isolation_provider/qubes.py
@@ -5,7 +5,7 @@ import subprocess
 import sys
 import zipfile
 from pathlib import Path
-from typing import IO, Callable, Optional
+from typing import IO

 from ..document import Document
 from ..updater.signatures import is_container_tar_bundled
@@ -49,6 +49,7 @@ class Qubes(IsolationProvider):

         if dev_mode:
             assert p.stdin is not None
+            assert conv_mod_path is not None
             # Send the dangerzone module first.
             self.teleport_dz_module(conv_mod_path, p.stdin)

@@ -84,7 +85,7 @@ class Qubes(IsolationProvider):
         if p.stdout:
             p.stdout.close()

-    def teleport_dz_module(self, conv_path: Optional[str], wpipe: IO[bytes]) -> None:
+    def teleport_dz_module(self, conv_path: str, wpipe: IO[bytes]) -> None:
         """Send the dangerzone module to another qube, as a zipfile."""
         # Grab the absolute file path of the dangerzone module.
         temp_file = io.BytesIO()