diff --git a/libc/unistd/ptsname_r.c b/libc/unistd/ptsname_r.c
index 1ed067b..2fa4c3d 100644
--- a/libc/unistd/ptsname_r.c
+++ b/libc/unistd/ptsname_r.c
@@ -32,7 +32,7 @@
 #include <errno.h>
 #include <string.h>
 
-char*  ptsname_r( int  fd, char*  buf, size_t  buflen)
+int    ptsname_r( int  fd, char*  buf, size_t  buflen)
 {
     unsigned int  pty_num;
     char          buff[64];
@@ -40,17 +40,19 @@
 
     if (buf == NULL) {
         errno = EINVAL;
-        return NULL;
+        return -1;
     }
 
-    if ( ioctl( fd, TIOCGPTN, &pty_num ) != 0 )
-        return NULL;
+    if ( ioctl( fd, TIOCGPTN, &pty_num ) != 0 ) {
+        errno = ENOTTY;
+        return -1;
+    }
 
     len = snprintf( buff, sizeof(buff), "/dev/pts/%u", pty_num );
     if (len+1 > (int)buflen) {
         errno = ERANGE;
-        return NULL;
+        return -1;
     }
     memcpy( buf, buff, len+1 );
-    return buf;
+    return 0;
 }