diff --git a/dangerzone/__init__.py b/dangerzone/__init__.py
index f029398..a67ebcf 100644
--- a/dangerzone/__init__.py
+++ b/dangerzone/__init__.py
@@ -4,6 +4,12 @@ import sys
 
 logger = logging.getLogger(__name__)
 
+# Call freeze_support() to avoid passing unknown options to the subprocess.
+# See https://github.com/freedomofpress/dangerzone/issues/873
+import multiprocessing
+
+multiprocessing.freeze_support()
+
 
 try:
     from . import vendor  # type: ignore [attr-defined]
diff --git a/dangerzone/gui/main_window.py b/dangerzone/gui/main_window.py
index 0f9b79c..fd86817 100644
--- a/dangerzone/gui/main_window.py
+++ b/dangerzone/gui/main_window.py
@@ -3,7 +3,6 @@ import os
 import platform
 import tempfile
 import typing
-from multiprocessing import freeze_support
 from multiprocessing.pool import ThreadPool
 from pathlib import Path
 from typing import List, Optional
@@ -1238,9 +1237,6 @@ class DocumentsListWidget(QtWidgets.QListWidget):
     def start_conversion(self) -> None:
         if not self.thread_pool_initized:
             max_jobs = self.dangerzone.isolation_provider.get_max_parallel_conversions()
-            # Call freeze_support() to avoid passing unknown options to the subprocess.
-            # See https://github.com/freedomofpress/dangerzone/issues/873
-            freeze_support()
             self.thread_pool = ThreadPool(max_jobs)
 
         for doc in self.docs_list: