Index: Python/sysmodule.c
===================================================================
--- Python/sysmodule.c	(révision 85302)
+++ Python/sysmodule.c	(copie de travail)
@@ -1659,12 +1659,14 @@
 
 #ifdef HAVE_REALPATH
 static wchar_t*
-_wrealpath(const wchar_t *path, wchar_t *resolved_path)
+_wrealpath(const wchar_t *path, wchar_t *resolved_path, size_t resolved_size)
 {
     char *cpath;
     char cresolved_path[PATH_MAX];
     char *res;
     size_t r;
+    PyObject *unicode;
+
     cpath = _Py_wchar2char(path);
     if (cpath == NULL) {
         errno = EINVAL;
@@ -1674,8 +1676,13 @@
     PyMem_Free(cpath);
     if (res == NULL)
         return NULL;
-    r = mbstowcs(resolved_path, cresolved_path, PATH_MAX);
-    if (r == (size_t)-1 || r >= PATH_MAX) {
+    unicode = PyUnicode_DecodeFSDefault(cresolved_path);
+    if (unicode == NULL)
+        return NULL;
+    r = PyUnicode_AsWideChar((PyUnicodeObject*)unicode,
+        resolved_path, resolved_size);
+    Py_DECREF(unicode);
+    if (r == -1 || r == resolved_size) {
         errno = EINVAL;
         return NULL;
     }
@@ -1769,9 +1776,8 @@
 #else /* All other filename syntaxes */
     if (_HAVE_SCRIPT_ARGUMENT(argc, argv)) {
 #if defined(HAVE_REALPATH)
-        if (_wrealpath(argv0, fullpath)) {
+        if (_wrealpath(argv0, fullpath, sizeof(fullpath)/sizeof(fullpath[0])))
             argv0 = fullpath;
-        }
 #endif
         p = wcsrchr(argv0, SEP);
     }