-/* Copyright (C) 1992, 1995-2002, 2005-2011 Free Software Foundation, Inc.
+/* Copyright (C) 1992, 1995-2002, 2005-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
This program is free software: you can redistribute it and/or modify
#endif
#if _LIBC
-/* This lock protects against simultaneous modifications of `environ'. */
+/* This lock protects against simultaneous modifications of 'environ'. */
# include <bits/libc-lock.h>
__libc_lock_define_initialized (static, envlock)
# define LOCK __libc_lock_lock (envlock)
#else /* HAVE_UNSETENV */
# undef unsetenv
+# if !HAVE_DECL_UNSETENV
+# if VOID_UNSETENV
+extern void unsetenv (const char *);
+# else
+extern int unsetenv (const char *);
+# endif
+# endif
/* Call the underlying unsetenv, in case there is hidden bookkeeping
that needs updating beyond just modifying environ. */