diff --git a/exec.c b/exec.c
index 7ed7183..41273df 100644
--- a/exec.c
+++ b/exec.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.191 2017/03/22 00:20:51 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/exec.c,v 1.192 2017/04/02 13:08:06 tg Exp $");
 
 #ifndef MKSH_DEFAULT_EXECSHELL
 #define MKSH_DEFAULT_EXECSHELL	MKSH_UNIXROOT "/bin/sh"
@@ -1136,7 +1136,7 @@ findcom(const char *name, int flags)
 	union mksh_cchack npath;
 
 	if (mksh_vdirsep(name)
-#ifdef __OS2__
+#ifdef MKSH_DOSPATH
 	    && (strcmp(name, T_builtin) != 0)
 #endif
 	    ) {
diff --git a/misc.c b/misc.c
index 50e5388..c560958 100644
--- a/misc.c
+++ b/misc.c
@@ -30,7 +30,7 @@
 #include <grp.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.253 2017/03/26 00:10:24 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.254 2017/04/02 13:08:06 tg Exp $");
 
 #define KSH_CHVT_FLAG
 #ifdef MKSH_SMALL
@@ -1705,7 +1705,7 @@ simplify_path(char *p)
 	case 0:
 		return;
 	case '/':
-#ifdef __OS2__
+#ifdef MKSH_DOSPATH
 	case '\\':
 #endif
 		/* exactly two leading slashes? (SUSv4 3.266) */
diff --git a/sh.h b/sh.h
index 6efbfc6..dd50312 100644
--- a/sh.h
+++ b/sh.h
@@ -175,7 +175,7 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.798 2017/03/26 00:10:25 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.799 2017/04/02 13:08:07 tg Exp $");
 #endif
 #define MKSH_VERSION "R54 2017/03/25"
 
@@ -392,13 +392,21 @@ struct rusage {
 #endif
 
 #ifdef __OS2__
+#define MKSH_UNIXROOT	"/@unixroot"
+#define MKSH_DOSPATH
+#else
+#define MKSH_UNIXROOT	""
+#endif
+
+#ifdef MKSH_DOSPATH
+#ifndef __GNUC__
+# error GCC extensions needed later on
+#endif
 #define MKSH_PATHSEPS	";"
 #define MKSH_PATHSEPC	';'
-#define MKSH_UNIXROOT	"/@unixroot"
 #else
 #define MKSH_PATHSEPS	":"
 #define MKSH_PATHSEPC	':'
-#define MKSH_UNIXROOT	""
 #endif
 
 #if !HAVE_FLOCK_DECL
@@ -2405,9 +2413,6 @@ EXTERN bool tty_hasstate;	/* true if tty_state is valid */
 extern int tty_init_fd(void);	/* initialise tty_fd, tty_devtty */
 
 #ifdef __OS2__
-#ifndef __GNUC__
-# error oops?
-#endif
 #define binopen2(path,flags)		__extension__({			\
 	int binopen2_fd = open((path), (flags) | O_BINARY);		\
 	if (binopen2_fd >= 0)						\
@@ -2420,6 +2425,12 @@ extern int tty_init_fd(void);	/* initialise tty_fd, tty_devtty */
 		setmode(binopen3_fd, O_BINARY);				\
 	(binopen3_fd);							\
 })
+#else
+#define binopen2(path,flags)		open((path), (flags) | O_BINARY)
+#define binopen3(path,flags,mode)	open((path), (flags) | O_BINARY, (mode))
+#endif
+
+#ifdef MKSH_DOSPATH
 #define mksh_abspath(s)			__extension__({			\
 	const char *mksh_abspath_s = (s);				\
 	(mksh_cdirsep(mksh_abspath_s[0]) ||				\
@@ -2436,8 +2447,6 @@ extern int tty_init_fd(void);	/* initialise tty_fd, tty_devtty */
  * can merge this upstream, but good job so far @komh, thanks!
  */
 #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_cdirsep(c)			((c) == '/')
 #define mksh_sdirsep(s)			strchr((s), '/')