diff --git a/src/allmydata/test/test_windows.py b/src/allmydata/test/test_windows.py
index ef113d9e8..02b05e5d1 100644
--- a/src/allmydata/test/test_windows.py
+++ b/src/allmydata/test/test_windows.py
@@ -181,6 +181,7 @@ class UnicodeOutputTests(SyncTestCase):
         automatic UTF-8 encoding.
         """
         working_path = FilePath(self.mktemp())
+        working_path.makedirs()
         script = working_path.child("script.py")
         script.setContent(dedent(
             """