diff --git a/eval.c b/eval.c
index 645b7dc..4bcc2fe 100644
--- a/eval.c
+++ b/eval.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/eval.c,v 1.217 2018/01/14 00:03:02 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/eval.c,v 1.218 2018/01/14 00:22:27 tg Exp $");
 
 /*
  * string expansion
@@ -897,7 +897,7 @@ expand(
 				--newlines;
 			} else {
 				while ((c = shf_getc(x.u.shf)) == 0 ||
-				    ctype(c, C_NL)) {
+				    cinttype(c, C_NL)) {
 #ifdef MKSH_WITH_TEXTMODE
 					if (c == '\r') {
 						c = shf_getc(x.u.shf);
diff --git a/lex.c b/lex.c
index 88a5774..55ecbdd 100644
--- a/lex.c
+++ b/lex.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.242 2018/01/14 00:03:02 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/lex.c,v 1.243 2018/01/14 00:22:28 tg Exp $");
 
 /*
  * states while lexing word
@@ -248,7 +248,7 @@ yylex(int cf)
 
 	/* collect non-special or quoted characters to form word */
 	while (!((c = getsc()) == 0 ||
-	    ((state == SBASE || state == SHEREDELIM) && ctype(c, C_LEX1)))) {
+	    ((state == SBASE || state == SHEREDELIM) && cinttype(c, C_LEX1)))) {
 		if (state == SBASE &&
 		    subshell_nesting_type == ORD(/*{*/ '}') &&
 		    (unsigned int)c == ORD(/*{*/ '}'))
@@ -299,7 +299,7 @@ yylex(int cf)
 			}
 			/* FALLTHROUGH */
  Sbase1:		/* includes *(...|...) pattern (*+?@!) */
-			if (ctype(c, C_PATMO)) {
+			if (cinttype(c, C_PATMO)) {
 				c2 = getsc();
 				if ((unsigned int)c2 == ORD('(' /*)*/)) {
 					*wp++ = OPAT;
diff --git a/sh.h b/sh.h
index d286d30..be151cb 100644
--- a/sh.h
+++ b/sh.h
@@ -182,7 +182,7 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.853 2018/01/14 00:09:34 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.854 2018/01/14 00:22:29 tg Exp $");
 #endif
 #define MKSH_VERSION "R56 2017/10/17"
 
@@ -1516,6 +1516,9 @@ extern void ebcdic_init(void);
 /* new fast character classes */
 #define ctype(c,t)	tobool(ksh_ctypes[ord(c)] & (t))
 /* helper functions */
+#define cinttype(c,t)	(intischar(c) ? \
+			tobool(ksh_ctypes[(unsigned char)(c)] & (t)) : 0)
+#define intischar(i)	((i) >= 0 && (i) <= 0xFF)
 #define ksh_isdash(s)	tobool(ord((s)[0]) == '-' && ord((s)[1]) == '\0')
 /* invariant distance even in EBCDIC */
 #define ksh_tolower(c)	(ctype(c, C_UPPER) ? (c) - 'A' + 'a' : (c))
diff --git a/syn.c b/syn.c
index 421cea3..e4c38e3 100644
--- a/syn.c
+++ b/syn.c
@@ -24,7 +24,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/syn.c,v 1.126 2018/01/14 00:03:04 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/syn.c,v 1.127 2018/01/14 00:22:30 tg Exp $");
 
 struct nesting_state {
 	int start_token;	/* token than began nesting (eg, FOR) */
@@ -95,7 +95,7 @@ yyparse(bool doalias)
 	c = tpeek(0);
 	if (c == 0 && !outtree)
 		outtree = newtp(TEOF);
-	else if (!ctype(c, C_LF | C_NUL))
+	else if (!cinttype(c, C_LF | C_NUL))
 		syntaxerr(NULL);
 }