diff --git a/bin/tools/misc.py b/bin/tools/misc.py
index c28a56f2d10..e4b2843662f 100644
--- a/bin/tools/misc.py
+++ b/bin/tools/misc.py
@@ -192,7 +192,9 @@ def file_open(name, mode="r", subdir='addons'):
 		if zipfile.is_zipfile(head+'.zip'):
 			import StringIO
 			zfile = zipfile.ZipFile(head+'.zip')
-			return StringIO.StringIO(zfile.read(os.path.join(os.path.basename(head), zipname)))
+			return StringIO.StringIO(zfile.read(os.path.join(
+				os.path.basename(head), zipname).replace(
+					os.sep, '/')))
 	if os.path.isfile(name):
 		return file(name, mode)