diff --git a/misc.c b/misc.c
index 5241d68..3c177ee 100644
--- a/misc.c
+++ b/misc.c
@@ -32,7 +32,7 @@
 #include <grp.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.281 2017/10/11 19:06:44 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.282 2017/10/11 20:46:14 tg Exp $");
 
 #define KSH_CHVT_FLAG
 #ifdef MKSH_SMALL
@@ -1785,7 +1785,7 @@ do_realpath(const char *upath)
 				}
 #ifdef MKSH_DOSPATH
 				/* drive letter? */
-				if (ctype(ip[0], C_ALPHA) && ip[1] == ':') {
+				if (mksh_drvltr(ip)) {
 					/* keep it */
 					Xput(xs, xp, *ip++);
 					Xput(xs, xp, *ip++);
@@ -1948,6 +1948,8 @@ make_path(const char *cwd, const char *file,
  * ..					..
  * ./foo				foo
  * foo/../../../bar			../../bar
+ * C:/../foo				C:/foo
+ * C:../foo				C:../foo
  */
 void
 simplify_path(char *p)
@@ -1956,6 +1958,12 @@ simplify_path(char *p)
 	size_t len;
 	bool needslash;
 
+#ifdef MKSH_DOSPATH
+	/* keep drive letter */
+	if (mksh_drvltr(p))
+		p += 2;
+#endif
+
 	switch (*p) {
 	case 0:
 		return;