diff --git a/misc.c b/misc.c
index 491a1be..f53aa61 100644
--- a/misc.c
+++ b/misc.c
@@ -32,7 +32,7 @@
 #include <grp.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.267 2017/04/28 03:28:18 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.268 2017/04/28 03:46:49 tg Exp $");
 
 #define KSH_CHVT_FLAG
 #ifdef MKSH_SMALL
@@ -937,7 +937,7 @@ ascstrcmp(const void *s1, const void *s2)
 			return (0);
 		++cp2;
 	}
-	return ((int)asc(*cp1) - (int)asc(*cp2));
+	return ((int)asciibetical(*cp1) - (int)asciibetical(*cp2));
 }
 
 int
@@ -1098,7 +1098,7 @@ print_value_quoted(struct shf *shf, const char *s)
 	bool inquote = true;
 
 	/* first, check whether any quotes are needed */
-	while (asc(c = *p++) >= 32)
+	while (rtt2asc(c = *p++) >= 32)
 		if (ctype(c, C_QUOTE | C_SPC))
 			inquote = false;
 
diff --git a/sh.h b/sh.h
index 8543e8e..da3da68 100644
--- a/sh.h
+++ b/sh.h
@@ -175,7 +175,7 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.825 2017/04/28 03:28:18 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.826 2017/04/28 03:46:50 tg Exp $");
 #endif
 #define MKSH_VERSION "R55 2017/04/27"
 
@@ -1467,13 +1467,14 @@ EXTERN char ifs0;
 
 /* identity transform of octet */
 #define ord(c)		((unsigned int)(unsigned char)(c))
-/* one-way to-ascii-or-high conversion */
 #ifdef MKSH_EBCDIC
 EXTERN unsigned short ebcdic_map[256];
 EXTERN unsigned char ebcdic_rtt_toascii[256];
 EXTERN unsigned char ebcdic_rtt_fromascii[256];
 extern void ebcdic_init(void);
-#define asc(c)		((unsigned int)ebcdic_map[(unsigned char)(c)])
+/* one-way to-ascii-or-high conversion, for POSIX locale ordering */
+#define asciibetical(c)	((unsigned int)ebcdic_map[(unsigned char)(c)])
+/* two-way round-trip conversion, for general use */
 #define rtt2asc(c)	ebcdic_rtt_toascii[(unsigned char)(c)]
 #define asc2rtt(c)	ebcdic_rtt_fromascii[(unsigned char)(c)]
 /* control character foo */
@@ -1481,7 +1482,7 @@ extern void ebcdic_init(void);
 /* case-independent char comparison */
 #define ksh_eq(c,u,l)	(ord(c) == ord(u) || ord(c) == ord(l))
 #else
-#define asc(c)		ord(c)
+#define asciibetical(c)	ord(c)
 #define rtt2asc(c)	((unsigned char)(c))
 #define asc2rtt(c)	((unsigned char)(c))
 #define ksh_isctrl(c)	(((c) & 0x7F) < 0x20 || (c) == 0x7F)
@@ -1494,10 +1495,10 @@ extern void ebcdic_init(void);
 /* invariant distance even in EBCDIC */
 #define ksh_tolower(c)	(ctype(c, C_UPPER) ? (c) - 'A' + 'a' : (c))
 #define ksh_toupper(c)	(ctype(c, C_LOWER) ? (c) - 'a' + 'A' : (c))
-/* strictly speaking asc() here, but this works even in EBCDIC */
+/* strictly speaking rtt2asc() here, but this works even in EBCDIC */
 #define ksh_numdig(c)	(ord(c) - ord('0'))
-#define ksh_numuc(c)	(asc(c) - asc('A'))
-#define ksh_numlc(c)	(asc(c) - asc('a'))
+#define ksh_numuc(c)	(rtt2asc(c) - rtt2asc('A'))
+#define ksh_numlc(c)	(rtt2asc(c) - rtt2asc('a'))
 #define ksh_toctrl(c)	asc2rtt(ord(c) == ord('?') ? 0x7F : rtt2asc(c) & 0x9F)
 #define ksh_unctrl(c)	asc2rtt(rtt2asc(c) ^ 0x40U)