diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index 5c9388746f4..79ccf24d369 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -34,7 +34,7 @@ def tearDown(self):
 			os.unlink(self.filename)
 	
 	def createTempFile(self, crlf=0):
-		f = open(self.filename, "w")
+		f = open(self.filename, "wb")
 		if crlf:
 			data = self.DATA_CRLF
 		else: