diff --git a/black.py b/black.py
index c1cc080..8855c37 100644
--- a/black.py
+++ b/black.py
@@ -8,7 +8,7 @@
 import itertools
 import keyword
 import logging
-from multiprocessing import Manager
+from multiprocessing import Manager, freeze_support
 import os
 from pathlib import Path
 import pickle
@@ -3658,6 +3658,7 @@ def patch_click() -> None:
 
 
 def patched_main() -> None:
+    freeze_support()
     patch_click()
     main()
 
diff --git a/blackd.py b/blackd.py
index c5aa29c..1a3b369 100644
--- a/blackd.py
+++ b/blackd.py
@@ -2,6 +2,7 @@
 from concurrent.futures import Executor, ProcessPoolExecutor
 from functools import partial
 import logging
+from multiprocessing import freeze_support
 
 from aiohttp import web
 import aiohttp_cors
@@ -130,6 +131,7 @@ async def handle(request: web.Request, executor: Executor) -> web.Response:
 
 
 def patched_main() -> None:
+    freeze_support()
     black.patch_click()
     main()