diff --git a/libc/termios/Make.defs b/libc/termios/Make.defs
index d20a5f95c71..e5a913d6e31 100644
--- a/libc/termios/Make.defs
+++ b/libc/termios/Make.defs
@@ -1,7 +1,7 @@
 ############################################################################
 # libc/misc/Make.defs
 #
-#   Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
+#   Copyright (C) 2011-2012, 2014 Gregory Nutt. All rights reserved.
 #   Author: Gregory Nutt <gnutt@nuttx.org>
 #
 # Redistribution and use in source and binary forms, with or without
@@ -41,7 +41,7 @@ ifeq ($(CONFIG_SERIAL_TERMIOS),y)
 
 # Add the termios C files to the build
 
-CSRCS += lib_cfgetspeed.c lib_cfsetspeed.c lib_tcflush.c
+CSRCS += lib_cfgetspeed.c lib_cfsetspeed.c lib_isatty.c lib_tcflush.c
 CSRCS += lib_tcgetattr.c lib_tcsetattr.c
 
 # Add the termios directory to the build
diff --git a/libc/termios/lib_isatty.c b/libc/termios/lib_isatty.c
index cf8e58332f6..6f0ec589fb2 100644
--- a/libc/termios/lib_isatty.c
+++ b/libc/termios/lib_isatty.c
@@ -1,14 +1,71 @@
-/* Added by Alan Carvalho de Assis
-   This code is from:
-	https://github.com/raggi/apue.2e/blob/master/termios/isatty.c
-   based on Advanced Programming in the UNIX Environment
-*/
+/****************************************************************************
+ * libc/termios/lib_tcflush.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Alan Carvalho de Assis
+ *
+ *   Source:
+ *     https://github.com/raggi/apue.2e/blob/master/termios/isatty.c
+ *     based on Advanced Programming in the UNIX Environment
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
 
 #include <termios.h>
 
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: isatty
+ *
+ * Description:
+ *   Return a non-zero (true) value if the file descriptor, fd, corresponds
+ *   to a TTYY.
+ *
+ *   NOTE: Nuttx, of course, does not have true TTYs in the sense that this
+ *   function is intended.  In this implementation, the function simply
+ *   returns true if the file descriptor is associated with a driver that
+ *   responds wo tcgetattr() without an error -- that it, the driver supports
+ *   the NuttX TCGETS ioctl command.
+ *
+ *   Of course, that can only be true if CONFIG_SERIAL_TERMIOS=y.
+ *
+ ****************************************************************************/
+
 int isatty(int fd)
 {
   struct termios ts;
-  return(tcgetattr(fd, &ts) != -1); /* true if no error (is a tty) */
+  return (tcgetattr(fd, &ts) >= 0);
 }
-