diff --git a/src/zope/publisher/tests/test_http.py b/src/zope/publisher/tests/test_http.py
index d8b59cd1..46dda013 100644
--- a/src/zope/publisher/tests/test_http.py
+++ b/src/zope/publisher/tests/test_http.py
@@ -74,7 +74,8 @@ def getLogMessage(self):
 
 # tempfiles have different types on different platforms, therefore use
 # this "canonical" way of finding out the type.
-TempFileType = tempfile.TemporaryFile().__class__
+with tempfile.TemporaryFile() as t:
+    TempFileType = t.__class__
 
 class HTTPInputStreamTests(unittest.TestCase):