diff --git a/edit.c b/edit.c
index 877da48..e21bdec 100644
--- a/edit.c
+++ b/edit.c
@@ -251,7 +251,7 @@ x_print_expansions(int nwords, char * const *words, bool is_command)
 				break;
 		/* All in same directory? */
 		if (i == nwords) {
-			while (prefix_len > 0 && !IS_DIR_SEP(words[0][prefix_len - 1]))
+			while (prefix_len > 0 && !mksh_dirsep(words[0][prefix_len - 1]))
 				prefix_len--;
 			use_copy = true;
 			XPinit(l, nwords + 1);
@@ -327,7 +327,7 @@ x_glob_hlp_tilde_and_rem_qchar(char *s, bool magic_flag)
 	 * and if so, discern "~foo/bar" and "~/baz" from "~blah";
 	 * if we have a directory part (the former), try to expand
 	 */
-	if (*s == '~' && (cp = ksh_strchr_dirsep(s)) != NULL) {
+	if (*s == '~' && (cp = mksh_strchr_dirsep(s)) != NULL) {
 		/* ok, so split into "~foo"/"bar" or "~"/"baz" */
 		*cp++ = 0;
 		/* try to expand the tilde */
@@ -577,7 +577,7 @@ x_locate_word(const char *buf, int buflen, int pos, int *startp,
 			 * like file globbing.
 			 */
 			for (p = start; p < end; p++)
-				if (IS_DIR_SEP(buf[p]))
+				if (mksh_dirsep(buf[p]))
 					break;
 			iscmd = p == end;
 		}
@@ -641,7 +641,7 @@ x_cf_glob(int *flagsp, const char *buf, int buflen, int pos, int *startp,
 			}
 		}
 
-		if (*toglob == '~' && !ksh_vstrchr_dirsep(toglob)) {
+		if (*toglob == '~' && !mksh_vstrchr_dirsep(toglob)) {
 			/* neither for '~foo' (but '~foo/bar') */
 			*flagsp |= XCF_IS_NOSPACE;
 			goto dont_add_glob;
@@ -731,11 +731,11 @@ x_basename(const char *s, const char *se)
 		return (0);
 
 	/* Skip trailing slashes */
-	for (p = se - 1; p > s && IS_DIR_SEP(*p); p--)
+	for (p = se - 1; p > s && mksh_dirsep(*p); p--)
 		;
-	for (; p > s && !IS_DIR_SEP(*p); p--)
+	for (; p > s && !mksh_dirsep(*p); p--)
 		;
-	if (IS_DIR_SEP(*p) && p + 1 < se)
+	if (mksh_dirsep(*p) && p + 1 < se)
 		p++;
 
 	return (p - s);
@@ -2800,7 +2800,7 @@ do_complete(
 	 * append a space if this is a single non-directory match
 	 * and not a parameter or homedir substitution
 	 */
-	if (nwords == 1 && !IS_DIR_SEP(words[0][nlen - 1]) &&
+	if (nwords == 1 && !mksh_dirsep(words[0][nlen - 1]) &&
 	    !(flags & XCF_IS_NOSPACE)) {
 		x_ins(" ");
 	}
@@ -5443,7 +5443,7 @@ complete_word(int cmd, int count)
 		 * append a space if this is a non-directory match
 		 * and not a parameter or homedir substitution
 		 */
-		if (match_len > 0 && !IS_DIR_SEP(match[match_len - 1]) &&
+		if (match_len > 0 && !mksh_dirsep(match[match_len - 1]) &&
 		    !(flags & XCF_IS_NOSPACE))
 			rval = putbuf(" ", 1, false);
 	}
diff --git a/eval.c b/eval.c
index 950bfe9..66f8a43 100644
--- a/eval.c
+++ b/eval.c
@@ -1535,7 +1535,7 @@ globit(XString *xs,	/* dest string */
 			 * SunOS 4.1.3 does this...
 			 */
 			if ((check & GF_EXCHECK) && xp > Xstring(*xs, xp) &&
-			    IS_DIR_SEP(xp[-1]) && !S_ISDIR(lstatb.st_mode) &&
+			    mksh_dirsep(xp[-1]) && !S_ISDIR(lstatb.st_mode) &&
 			    (!S_ISLNK(lstatb.st_mode) ||
 			    stat_check() < 0 || !S_ISDIR(statb.st_mode)))
 				return;
@@ -1545,7 +1545,7 @@ globit(XString *xs,	/* dest string */
 			 * directory
 			 */
 			if (((check & GF_MARKDIR) && (check & GF_GLOBBED)) &&
-			    xp > Xstring(*xs, xp) && !IS_DIR_SEP(xp[-1]) &&
+			    xp > Xstring(*xs, xp) && !mksh_dirsep(xp[-1]) &&
 			    (S_ISDIR(lstatb.st_mode) ||
 			    (S_ISLNK(lstatb.st_mode) && stat_check() > 0 &&
 			    S_ISDIR(statb.st_mode)))) {
@@ -1560,11 +1560,11 @@ globit(XString *xs,	/* dest string */
 
 	if (xp > Xstring(*xs, xp))
 		*xp++ = '/';
-	while (IS_DIR_SEP(*sp)) {
+	while (mksh_dirsep(*sp)) {
 		Xcheck(*xs, xp);
 		*xp++ = *sp++;
 	}
-	np = ksh_strchr_dirsep(sp);
+	np = mksh_strchr_dirsep(sp);
 	if (np != NULL) {
 		se = np;
 		/* don't assume '/', can be multiple kinds */
@@ -1672,7 +1672,7 @@ maybe_expand_tilde(const char *p, XString *dsp, char **dpp, bool isassign)
 
 	Xinit(ts, tp, 16, ATEMP);
 	/* : only for DOASNTILDE form */
-	while (p[0] == CHAR && !IS_DIR_SEP(p[1]) && (!isassign || p[1] != ':'))
+	while (p[0] == CHAR && !mksh_dirsep(p[1]) && (!isassign || p[1] != ':'))
 	{
 		Xcheck(ts, tp);
 		*tp++ = p[1];
diff --git a/exec.c b/exec.c
index ab4ffb5..8992a69 100644
--- a/exec.c
+++ b/exec.c
@@ -703,7 +703,7 @@ comexec(struct op *t, struct tbl * volatile tp, const char **ap,
 		rv = subst_exstat;
 		goto Leave;
 	} else if (!tp) {
-		if (Flag(FRESTRICTED) && ksh_vstrchr_dirsep(cp)) {
+		if (Flag(FRESTRICTED) && mksh_vstrchr_dirsep(cp)) {
 			warningf(true, "%s: %s", cp, "restricted");
 			rv = 1;
 			goto Leave;
@@ -993,7 +993,7 @@ scriptexec(struct op *tp, const char **ap)
 		 * Search shell/interpreter name without directory in PATH
 		 * if specified path does not exist
 		 */
-		if (ksh_vstrchr_dirsep(sh) && !search_path(sh, path, X_OK, NULL)) {
+		if (mksh_vstrchr_dirsep(sh) && !search_path(sh, path, X_OK, NULL)) {
 			cp = search_path(_getname(sh), path, X_OK, NULL);
 			if (cp)
 				sh = cp;
@@ -1183,7 +1183,7 @@ findcom(const char *name, int flags)
 	char *fpath;
 	union mksh_cchack npath;
 
-	if (ksh_vstrchr_dirsep(name)) {
+	if (mksh_vstrchr_dirsep(name)) {
 		insert = 0;
 		/* prevent FPATH search below */
 		flags &= ~FC_FUNC;
@@ -1330,7 +1330,7 @@ search_path(const char *name, const char *lpath,
 	size_t namelen;
 	int ec = 0, ev;
 
-	if (ksh_vstrchr_dirsep(name)) {
+	if (mksh_vstrchr_dirsep(name)) {
 		if ((ec = search_access(name, mode)) == 0) {
  search_path_ok:
 			if (errnop)
diff --git a/main.c b/main.c
index 9bf667d..b5f3d08 100644
--- a/main.c
+++ b/main.c
@@ -225,7 +225,7 @@ main_init(int argc, const char *argv[], Source **sp, struct block **lp)
 	ccp = kshname;
 	goto begin_parse_kshname;
 	while ((i = ccp[argi++])) {
-		if (IS_DIR_SEP(i)) {
+		if (mksh_dirsep(i)) {
 			ccp += argi;
  begin_parse_kshname:
 			argi = 0;
diff --git a/misc.c b/misc.c
index da20bb2..99e169f 100644
--- a/misc.c
+++ b/misc.c
@@ -387,7 +387,7 @@ parse_args(const char **argv,
 		 */
 		if (*p != '-')
 			for (q = p; *q; )
-				if (IS_DIR_SEP(*q++))
+				if (mksh_dirsep(*q++))
 					p = q;
 		Flag(FLOGIN) = (*p == '-');
 		opts = cmd_opts;
@@ -1440,14 +1440,14 @@ do_realpath(const char *upath)
 
 	while (*ip) {
 		/* skip slashes in input */
-		while (IS_DIR_SEP(*ip))
+		while (mksh_dirsep(*ip))
 			++ip;
 		if (!*ip)
 			break;
 
 		/* get next pathname component from input */
 		tp = ip;
-		while (*ip && !IS_DIR_SEP(*ip))
+		while (*ip && !mksh_dirsep(*ip))
 			++ip;
 		len = ip - tp;
 
@@ -1459,7 +1459,7 @@ do_realpath(const char *upath)
 			else if (len == 2 && tp[1] == '.') {
 				/* strip off last pathname component */
 				while (xp > Xstring(xs, xp))
-					if (IS_DIR_SEP(*--xp))
+					if (mksh_dirsep(*--xp))
 						break;
 				/* then continue with the next one */
 				continue;
@@ -1482,7 +1482,7 @@ do_realpath(const char *upath)
 			/* lstat failed */
 			if (errno == ENOENT) {
 				/* because the pathname does not exist */
-				while (IS_DIR_SEP(*ip))
+				while (mksh_dirsep(*ip))
 					/* skip any trailing slashes */
 					++ip;
 				/* no more components left? */
@@ -1542,7 +1542,7 @@ do_realpath(const char *upath)
 				/* assert: xp == xs.beg => start of path */
 
 				/* exactly two leading slashes? (SUSv4 3.266) */
-				if (IS_DIR_SEP(ip[1]) && !IS_DIR_SEP(ip[2])) {
+				if (mksh_dirsep(ip[1]) && !mksh_dirsep(ip[2])) {
 					/* keep them, e.g. for UNC pathnames */
 					Xput(xs, xp, '/');
 				}
@@ -1567,7 +1567,7 @@ do_realpath(const char *upath)
 	 * if source path had a trailing slash, check if target path
 	 * is not a non-directory existing file
 	 */
-	if (ip > ipath && IS_DIR_SEP(ip[-1])) {
+	if (ip > ipath && mksh_dirsep(ip[-1])) {
 		if (stat(Xstring(xs, xp), &sb)) {
 			if (errno != ENOENT)
 				goto notfound;
@@ -1638,7 +1638,7 @@ make_path(const char *cwd, const char *file,
 
 			if (c == '.')
 				c = file[2];
-			if (IS_DIR_SEP(c) || c == '\0')
+			if (mksh_dirsep(c) || c == '\0')
 				use_cdpath = false;
 		}
 
@@ -1660,7 +1660,7 @@ make_path(const char *cwd, const char *file,
 			XcheckN(*xsp, xp, len);
 			memcpy(xp, cwd, len);
 			xp += len;
-			if (!IS_DIR_SEP(cwd[len - 1]))
+			if (!mksh_dirsep(cwd[len - 1]))
 				Xput(*xsp, xp, '/');
 		}
 		*phys_pathp = Xlength(*xsp, xp);
@@ -1668,7 +1668,7 @@ make_path(const char *cwd, const char *file,
 			XcheckN(*xsp, xp, plen);
 			memcpy(xp, plist, plen);
 			xp += plen;
-			if (!IS_DIR_SEP(plist[plen - 1]))
+			if (!mksh_dirsep(plist[plen - 1]))
 				Xput(*xsp, xp, '/');
 			rval = 1;
 		}
@@ -1713,7 +1713,7 @@ simplify_path(char *p)
 	case '\\':
 #endif
 		/* exactly two leading slashes? (SUSv4 3.266) */
-		if (IS_DIR_SEP(p[1]) && !IS_DIR_SEP(p[2]))
+		if (mksh_dirsep(p[1]) && !mksh_dirsep(p[2]))
 			/* keep them, e.g. for UNC pathnames */
 			++p;
 		needslash = true;
@@ -1725,14 +1725,14 @@ simplify_path(char *p)
 
 	while (*ip) {
 		/* skip slashes in input */
-		while (IS_DIR_SEP(*ip))
+		while (mksh_dirsep(*ip))
 			++ip;
 		if (!*ip)
 			break;
 
 		/* get next pathname component from input */
 		tp = ip;
-		while (*ip && !IS_DIR_SEP(*ip))
+		while (*ip && !mksh_dirsep(*ip))
 			++ip;
 		len = ip - tp;
 
@@ -1752,7 +1752,7 @@ simplify_path(char *p)
  strip_last_component:
 					/* strip off last pathname component */
 					while (dp > sp)
-						if (IS_DIR_SEP(*--dp))
+						if (mksh_dirsep(*--dp))
 							break;
 				} else {
 					/* relative path, at its beginning */
diff --git a/sh.h b/sh.h
index dbc3658..48d9943 100644
--- a/sh.h
+++ b/sh.h
@@ -302,42 +302,6 @@ struct rusage {
 	} while (/* CONSTCOND */ 0)
 #endif
 
-#ifdef __OS2__
-#define UNIXROOT	"/@unixroot"
-#define PATH_SEP	';'
-#define PATH_SEP_STR	";"
-#define IS_DIR_SEP(c) ({		\
-	char _ch_ = (c);				\
-	(_ch_ == '/' || _ch_ == '\\');	\
-})
-#define IS_ABS_PATH(x) ({	\
-	const char *_p_ = (x);	\
-	((ksh_isalphx(_p_[0]) && _p_[1] == ':') || IS_DIR_SEP(_p_[0]));	\
-})
-#define ksh_strchr_dirsep(s) ({				\
-	const char *_p_ = (s);					\
-	const char *_p1_ = strchr(_p_, '/');		\
-	const char *_p2_ = strchr(_p_, '\\');		\
-	const char *_p3_ = ((ksh_isalphx(_p_[0]) && _p_[1] == ':')	\
-	                    ? (_p_ + 1) : NULL );	\
-	_p1_ = _p1_ > _p2_ ? _p1_ : _p2_;		\
-	((char *)(_p1_ > _p3_ ? _p1_ : _p3_));	\
-})
-#define ksh_vstrchr_dirsep(s) ({			\
-	const char *_p_ = (s);					\
-	(vstrchr((_p_), '/') || vstrchr((_p_), '\\') ||		\
-	    (ksh_isalphx(_p_[0]) && _p_[1] == ':'));	\
-})
-#else
-#define UNIXROOT	""
-#define PATH_SEP	':'
-#define PATH_SEP_STR	":"
-#define IS_DIR_SEP(c)	((c) == '/')
-#define IS_ABS_PATH(x)	(IS_DIR_SEP((x)[0]))
-#define ksh_strchr_dirsep(s)	(strchr((s), '/'))
-#define ksh_vstrchr_dirsep(s)	(vstrchr((s), '/'))
-#endif
-
 #ifdef MKSH__NO_PATH_MAX
 #undef PATH_MAX
 #else
@@ -1109,7 +1073,7 @@ EXTERN mksh_ari_t x_lins E_INIT(24);	/* tty lines */
 #if defined(ANDROID)
 #define MKSH_DEFAULT_PROFILEDIR	"/system/etc"
 #else
-#define MKSH_DEFAULT_PROFILEDIR	UNIXROOT "/etc"
+#define MKSH_DEFAULT_PROFILEDIR	MKSH_UNIXROOT "/etc"
 #endif
 #endif
 
@@ -2156,13 +2120,41 @@ extern int tty_init_fd(void);	/* initialise tty_fd, tty_devtty */
 })
 #define mksh_abspath(s)			__extension__({			\
 	const char *mksh_abspath_s = (s);				\
-	(mksh_abspath_s[0] == '/' || (ksh_isalphx(mksh_abspath_s[0]) &&	\
+	(mksh_dirsep(mksh_abspath_s[0]) || (ksh_isalphx(mksh_abspath_s[0]) &&	\
 	    mksh_abspath_s[1] == ':'));					\
 })
+#define mksh_dirsep(c)			__extension__({			\
+	char mksh_dirsep_c = (c);							\
+	(mksh_dirsep_c == '/' || mksh_dirsep_c == '\\');	\
+})
+#define mksh_strchr_dirsep(s)	__extension__({					\
+	const char *mksh_strchr_dirsep_p = (s);						\
+	const char *mksh_strchr_dirsep_p1 = strchr(mksh_strchr_dirsep_p, '/');	\
+	const char *mksh_strchr_dirsep_p2 = strchr(mksh_strchr_dirsep_p, '\\');	\
+	const char *mksh_strchr_dirsep_p3 =							\
+		((ksh_isalphx(mksh_strchr_dirsep_p[0]) &&				\
+		  mksh_strchr_dirsep_p[1] == ':')						\
+	                    ? (mksh_strchr_dirsep_p + 1) : NULL );	\
+	mksh_strchr_dirsep_p1 = mksh_strchr_dirsep_p1 > mksh_strchr_dirsep_p2 ?	\
+		mksh_strchr_dirsep_p1 : mksh_strchr_dirsep_p2;			\
+	((char *)(mksh_strchr_dirsep_p1 > mksh_strchr_dirsep_p3 ?	\
+		mksh_strchr_dirsep_p1 : mksh_strchr_dirsep_p3));		\
+})
+#define mksh_vstrchr_dirsep(s)	__extension__({					\
+	const char *mksh_vstrchr_dirsep_p = (s);					\
+	(vstrchr((mksh_vstrchr_dirsep_p), '/') || 					\
+	    vstrchr((mksh_vstrchr_dirsep_p), '\\') ||				\
+	    (ksh_isalphx(mksh_vstrchr_dirsep_p[0]) && 				\
+	        mksh_vstrchr_dirsep_p[1] == ':'));					\
+})
+
 #else
 #define binopen2(path,flags)		open((path), (flags) | O_BINARY)
 #define binopen3(path,flags,mode)	open((path), (flags) | O_BINARY, (mode))
 #define mksh_abspath(s)			((s)[0] == '/')
+#define mksh_dirsep(c)			((c) == '/')
+#define mksh_strchr_dirsep(s)	(strchr((s), '/'))
+#define mksh_vstrchr_dirsep(s)	(vstrchr((s), '/'))
 #endif
 
 /* be sure not to interfere with anyone else's idea about EXTERN */