diff -r 278dd7eb2f2b Python/pythonrun.c
--- a/Python/pythonrun.c	Fri Dec 13 14:33:01 2013 +0100
+++ b/Python/pythonrun.c	Fri Dec 13 17:29:58 2013 +0100
@@ -1166,6 +1166,14 @@ initstdio(void)
     encoding = _Py_StandardStreamEncoding;
     errors = _Py_StandardStreamErrors;
     if (!encoding || !errors) {
+        if (!errors) {
+            /* If LC_CTYPE uses the POSIX locale (aka "C locale"), use
+               the surrogateescape error handler by default. */
+            char *loc = setlocale(LC_CTYPE, NULL);
+            if (loc != NULL && strcmp(loc, "C") == 0)
+                errors = "surrogateescape";
+        }
+
         pythonioencoding = Py_GETENV("PYTHONIOENCODING");
         if (pythonioencoding) {
             char *err;