diff -r e5478b6b93b5 Lib/doctest.py
--- a/Lib/doctest.py	Sat Jun 23 10:06:56 2012 +0200
+++ b/Lib/doctest.py	Mon Jun 25 13:00:40 2012 +0200
@@ -216,8 +216,11 @@
                 # 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:
-        return f.read(), filename
+    try:
+        with open(filename) as f:
+            return f.read(), filename
+    except IOError as e:
+        sys.exit("Cannot read '{0}': {1}".format(filename, e))
 
 # Use sys.stdout encoding for ouput.
 _encoding = getattr(sys.__stdout__, 'encoding', None) or 'utf-8'