diff --git a/include/_tail_cc/sgtty.h b/include/_tail_cc/sgtty.h
index 1974720d3..b9113f8b7 100644
--- a/include/_tail_cc/sgtty.h
+++ b/include/_tail_cc/sgtty.h
@@ -13,7 +13,7 @@ struct sgttyb {
   char sg_ospeed;		/* output speed (not used) */
   char sg_erase;		/* erase character */
   char sg_kill;			/* kill character */
-#ifdef __USG
+#if defined(__USG) && !defined(_XENIX)
   int sg_flags;			/* mode flags */
 #else
   short sg_flags;		/* mode flags */
@@ -46,7 +46,11 @@ struct tchars {
 #  define CR2        0020000
 #  define CR3        0030000
 
+#if     defined(__USG) && !defined(_XENIX)
+#define XTABS	     0000002	/* do tab expansion */
+#else
 #define XTABS	     0006000	/* do tab expansion */
+#endif
 
 #define TBDELAY	     0006000
 #  define TAB0       0000000
@@ -68,8 +72,12 @@ struct tchars {
 #define ECHO	     0000010	/* echo input */
 #define LCASE	     0000004
 #define CBREAK	     0000002	/* enable cbreak mode */
+#if     defined(__BSD4_2) || defined(_XENIX)
 #define TANDEM	     0000001
-/*#define COOKED       0000000	/* neither CBREAK nor RAW */
+#else
+#define HUPCL	     0000001    /* unused ??? */
+#endif
+/*#define COOKED     0000000	/* neither CBREAK nor RAW */
 
 #ifdef __BDS4_2
 #define TIOCGETP (('t'<<8) | 8 | (6 << 16) | 0x40000000)
diff --git a/include/_tail_cc/sys/stat.h b/include/_tail_cc/sys/stat.h
index afa95aa04..802f2a31f 100644
--- a/include/_tail_cc/sys/stat.h
+++ b/include/_tail_cc/sys/stat.h
@@ -1,11 +1,11 @@
-/* $Header$ */
 /*
  * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
  * See the copyright notice in the ACK home directory, in the file "Copyright".
  */
+/* $Header$ */
 
-#ifndef _STAT_H
-#define _STAT_H
+#if	!defined(_SYS_STAT_H)
+#define	_SYS_STAT_H
 
 struct	stat {
 	dev_t	st_dev;
@@ -17,15 +17,15 @@ struct	stat {
 	dev_t	st_rdev;
 	off_t	st_size;
 	time_t	st_atime;
-#ifdef __BSD4_2
+#if	defined(__BSD4_2)
 	long	st_spare1;
 #endif
 	time_t	st_mtime;
-#ifdef __BSD4_2
+#if	defined(__BSD4_2)
 	long	st_spare2;
 #endif
 	time_t	st_ctime;
-#ifdef __BSD4_2
+#if	defined(__BSD4_2)
 	long	st_spare3;
 	long	st_blksize;
 	long	st_blocks;
@@ -38,8 +38,8 @@ struct	stat {
 #define	  S_IFCHR	0020000
 #define	  S_IFBLK	0060000
 #define	  S_IFREG	0100000
-#ifndef __BSD4_2
-#ifndef __USG
+#if	!defined(__BSD4_2)
+#if	!defined(__USG) && !defined(_POSIX_SOURCE)
 #define	  S_IFMPC	0030000
 #define	  S_IFMPB	0070000
 #else
@@ -56,4 +56,30 @@ struct	stat {
 #define	S_IWRITE	0000200
 #define	S_IEXEC		0000100
 
-#endif /* _STAT_H */
+#if	defined(__BSD4_2) || defined(_POSIX_SOURCE)
+#define	S_IRWXU		00700		/* owner:  rwx------ */
+#define	S_IRUSR		00400		/* owner:  r-------- */
+#define	S_IWUSR		00200		/* owner:  -w------- */
+#define	S_IXUSR		00100		/* owner:  --x------ */
+ 
+#define	S_IRWXG		00070		/* group:  ---rwx--- */
+#define	S_IRGRP		00040		/* group:  ---r----- */
+#define	S_IWGRP		00020		/* group:  ----w---- */
+#define	S_IXGRP		00010		/* group:  -----x--- */
+ 
+#define	S_IRWXO		00007		/* others: ------rwx */
+#define	S_IROTH		00004		/* others: ------r-- */ 
+#define	S_IWOTH		00002		/* others: -------w- */
+#define	S_IXOTH		00001		/* others: --------x */
+ 
+#if	defined(_POSIX_SOURCE)
+/* The following macros test st_mode (from POSIX Sec. 5.6.1.1.) */
+#define	S_ISREG(m)	((m & S_IFMT) == S_IFREG)	/* is a reg file */
+#define	S_ISDIR(m)	((m & S_IFMT) == S_IFDIR)	/* is a directory */
+#define	S_ISCHR(m)	((m & S_IFMT) == S_IFCHR)	/* is a char spec */
+#define	S_ISBLK(m)	((m & S_IFMT) == S_IFBLK)	/* is a block spec */
+#define	S_ISFIFO(m)	((m & S_IFMT) == S_IFIFO)	/* is a pipe/FIFO */
+#endif	/* _POSIX_SOURCE */
+#endif	/* BSD4_2 || _POSIX_SOURCE */
+
+#endif	/* _SYS_STAT_H */