diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index e9947e9..bb9f425 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1156,6 +1156,15 @@
     encoding = _Py_StandardStreamEncoding;
     errors = _Py_StandardStreamErrors;
     if (!encoding || !errors) {
+        if (!errors) {
+            /* When the LC_CTYPE locale is the POSIX locale ("C locale"),
+               stdin and stdout use the surrogateescape error handler by
+               default, instead of the strict error handler. */
+            char *loc = setlocale(LC_CTYPE, NULL);
+            if (loc != NULL && strcmp(loc, "C") == 0)
+                errors = "surrogateescape";
+        }
+
         pythonioencoding = Py_GETENV("PYTHONIOENCODING");
         if (pythonioencoding) {
             char *err;
@@ -1168,7 +1177,7 @@
             if (err) {
                 *err = '\0';
                 err++;
-                if (*err && !errors) {
+                if (*err && !_Py_StandardStreamErrors) {
                     errors = err;
                 }
             }