diff --git a/ChangeLog b/ChangeLog
index 50d9e9c4e3..9d2a25d582 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-05-06  Roland McGrath  <roland@hack.frob.com>
+
+	* sysdeps/posix/truncate.c (__truncate): Renamed from truncate.
+	Call __ names for open, ftruncate, and close.
+	For LENGTH==0 case, just use O_TRUNC rather than calling ftruncate.
+	(truncate): Define as weak alias.
+
 2013-05-06  Joseph Myers  <joseph@codesourcery.com>
 
 	* math/gen-libm-test.pl (parse_args): Initialize x before each
diff --git a/sysdeps/posix/truncate.c b/sysdeps/posix/truncate.c
index ae29be8106..7ef1400eb5 100644
--- a/sysdeps/posix/truncate.c
+++ b/sysdeps/posix/truncate.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1995-2013 Free Software Foundation, Inc.
+/* Truncate a file given by name.  Generic POSIX.1 version.
+   Copyright (C) 1995-2013 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -22,20 +23,22 @@
 
 /* Truncate PATH to LENGTH bytes.  */
 int
-truncate (path, length)
-     const char *path;
-     off_t length;
+__truncate (const char *path, off_t length)
 {
   int fd, ret, save;
 
-  fd = open (path, O_WRONLY);
+  fd = __open (path, O_WRONLY | (length == 0 ? O_TRUNC : 0));
   if (fd < 0)
     return -1;
 
-  ret = ftruncate (fd, length);
+  if (length == 0)
+    ret = 0;
+  else
+    ret = __ftruncate (fd, length);
   save = errno;
-  (void) close (fd);
+  (void) __close (fd);
   if (ret < 0)
     __set_errno (save);
   return ret;
 }
+weak_alias (__truncate, truncate)