diff --git a/libc/unistd/ptsname_r.c b/libc/unistd/ptsname_r.c
new file mode 100644
index 0000000..1ed067b
--- /dev/null
+++ b/libc/unistd/ptsname_r.c
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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.
+ *
+ * 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.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+#include <string.h>
+
+char*  ptsname_r( int  fd, char*  buf, size_t  buflen)
+{
+    unsigned int  pty_num;
+    char          buff[64];
+    int           len;
+
+    if (buf == NULL) {
+        errno = EINVAL;
+        return NULL;
+    }
+
+    if ( ioctl( fd, TIOCGPTN, &pty_num ) != 0 )
+        return NULL;
+
+    len = snprintf( buff, sizeof(buff), "/dev/pts/%u", pty_num );
+    if (len+1 > (int)buflen) {
+        errno = ERANGE;
+        return NULL;
+    }
+    memcpy( buf, buff, len+1 );
+    return buf;
+}