diff --git a/Lib/doctest.py b/Lib/doctest.py
index 86c9839..6811406 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -216,7 +216,7 @@
                 # get_data() opens files as 'rb', so one must do the equivalent
                 # conversion as universal newlines would do.
                 return file_contents.replace(os.linesep, '\n'), filename
-    with open(filename) as f:
+    with open(filename, 'U') as f:
         return f.read(), filename
 
 # Use sys.stdout encoding for ouput.