diff --git a/sh.h b/sh.h
index cc69eb5..8acdbb5 100644
--- a/sh.h
+++ b/sh.h
@@ -175,7 +175,7 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.828 2017/04/28 11:13:48 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.829 2017/04/28 11:31:51 tg Exp $");
 #endif
 #define MKSH_VERSION "R55 2017/04/27"
 
@@ -1492,7 +1492,7 @@ extern void ebcdic_init(void);
 #define ksh_isctrl(c)	((ord(c) & 0x7F) < 0x20 || (c) == 0x7F)
 #endif
 /* new fast character classes */
-#define ctype(c,t)	tobool(ksh_ctypes[rtt2asc(c)] & (t))
+#define ctype(c,t)	tobool(ksh_ctypes[ord(c)] & (t))
 /* helper functions */
 #define ksh_isdash(s)	tobool(ord((s)[0]) == '-' && ord((s)[1]) == '\0')
 /* invariant distance even in EBCDIC */
diff --git a/shf.c b/shf.c
index 6bf10bf..ac01d0c 100644
--- a/shf.c
+++ b/shf.c
@@ -25,7 +25,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/shf.c,v 1.91 2017/04/28 11:27:58 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/shf.c,v 1.92 2017/04/28 11:31:53 tg Exp $");
 
 /* flags to shf_emptybuf() */
 #define EB_READSW	0x01	/* about to switch to reading */
@@ -1209,12 +1209,21 @@ const uint32_t tpl_ctypes[128] = {
 void
 set_ifs(const char *s)
 {
+#if defined(MKSH_EBCDIC) || defined(MKSH_FAUX_EBCDIC)
+	int i = 256;
+
+	memset(ksh_ctypes, 0, sizeof(ksh_ctypes));
+	while (i--)
+		if (ebcdic_map[i] < 0x80U)
+			ksh_ctypes[i] = tpl_ctypes[ebcdic_map[i]];
+#else
 	memcpy(ksh_ctypes, tpl_ctypes, sizeof(tpl_ctypes));
 	memset((char *)ksh_ctypes + sizeof(tpl_ctypes), '\0',
 	    sizeof(ksh_ctypes) - sizeof(tpl_ctypes));
+#endif
 	ifs0 = *s;
 	while (*s)
-		ksh_ctypes[rtt2asc(*s++)] |= CiIFS;
+		ksh_ctypes[ord(*s++)] |= CiIFS;
 }
 
 #if defined(MKSH_EBCDIC) || defined(MKSH_FAUX_EBCDIC)