diff --git a/sh.decls.h b/sh.decls.h
index a863fede..395f5e7b 100644
--- a/sh.decls.h
+++ b/sh.decls.h
@@ -126,8 +126,8 @@ extern	int		  find_cmd	(Char *, int);
  * sh.exp.c
  */
 extern  Char		 *filetest      (Char *, Char ***, int);
-extern	tcsh_number_t 	  expr		(Char ***);
-extern	tcsh_number_t	  exp0		(Char ***, int);
+extern	unsigned tcsh_number_t 	  expr	(Char ***);
+extern	unsigned tcsh_number_t	  exp0	(Char ***, int);
 
 /*
  * sh.file.c
@@ -379,8 +379,8 @@ extern	void		  mypipe	(int *);
 extern	struct varent 	 *adrof1	(const Char *, struct varent *);
 extern	void		  doset		(Char **, struct command *);
 extern	void		  dolet		(Char **, struct command *);
-extern	Char		 *putn		(tcsh_number_t);
-extern	tcsh_number_t	  getn		(const Char *);
+extern	Char		 *putn		(unsigned tcsh_number_t);
+extern	unsigned tcsh_number_t	  getn	(const Char *);
 extern	Char		 *value1	(Char *, struct varent *);
 extern	void		  setcopy	(const Char *, const Char *, int);
 extern	void		  setv		(const Char *, Char *, int);
diff --git a/sh.err.c b/sh.err.c
index 9d9600ae..1ed53200 100644
--- a/sh.err.c
+++ b/sh.err.c
@@ -188,7 +188,9 @@ extern int enterhist;
 #define ERR_BADCOLORVAR	134
 #define ERR_EOF		135
 #define ERR_UNAVAILABLE	136
-#define NO_ERRORS	137
+#define ERR_DIVOF	137
+#define ERR_MODOF	138
+#define NO_ERRORS	139
 
 static const char *elst[NO_ERRORS] INIT_ZERO_STRUCT;
 
@@ -367,7 +369,8 @@ errinit(void)
     elst[ERR_BADCOLORVAR] = CSAVS(1, 137, "Unknown %s color variable '%c%c'");
     elst[ERR_EOF] = CSAVS(1, 138, "Unexpected end of file");
     elst[ERR_UNAVAILABLE] = CSAVS(1, 139, "%s: Feature is not available for this platform");
-
+    elst[ERR_DIVOF] = CSAVS(1, 140, "Division overflow");
+    elst[ERR_MODOF] = CSAVS(1, 141, "Mod overflow");
 }
 
 /* Cleanup data. */
diff --git a/sh.exp.c b/sh.exp.c
index f291a59d..925f776f 100644
--- a/sh.exp.c
+++ b/sh.exp.c
@@ -51,11 +51,11 @@
 #define NOTEQMATCH 8
 
 static	int	   sh_access	(const Char *, int);
-static	tcsh_number_t  exp1		(Char ***, int);
-static	tcsh_number_t  exp2x	(Char ***, int);
-static	tcsh_number_t  exp2a	(Char ***, int);
-static	tcsh_number_t  exp2b	(Char ***, int);
-static	tcsh_number_t  exp2c	(Char ***, int);
+static	unsigned tcsh_number_t  exp1	(Char ***, int);
+static	unsigned tcsh_number_t  exp2x	(Char ***, int);
+static	unsigned tcsh_number_t  exp2a	(Char ***, int);
+static	unsigned tcsh_number_t  exp2b	(Char ***, int);
+static	unsigned tcsh_number_t  exp2c	(Char ***, int);
 static	Char 	  *exp3		(Char ***, int);
 static	Char 	  *exp3a	(Char ***, int);
 static	Char 	  *exp4		(Char ***, int);
@@ -63,7 +63,7 @@ static	Char 	  *exp5		(Char ***, int);
 static	Char 	  *exp6		(Char ***, int);
 static	void	   evalav	(Char **);
 static	int	   isa		(Char *, int);
-static	tcsh_number_t  egetn	(const Char *);
+static	unsigned tcsh_number_t  egetn	(const Char *);
 
 #ifdef EDEBUG
 static	void	   etracc	(const char *, const Char *, Char ***);
@@ -177,20 +177,20 @@ sh_access(const Char *fname, int mode)
 #endif /* !POSIX */
 }
 
-tcsh_number_t
+unsigned tcsh_number_t
 expr(Char ***vp)
 {
     return (exp0(vp, 0));
 }
 
-tcsh_number_t
+unsigned tcsh_number_t
 exp0(Char ***vp, int ignore)
 {
-    tcsh_number_t p1 = exp1(vp, ignore);
+    unsigned tcsh_number_t p1 = exp1(vp, ignore);
 
     etraci("exp0 p1", p1, vp);
     while (**vp && eq(**vp, STRor2)) {
-	int p2;
+	unsigned tcsh_number_t p2;
 
 	(*vp)++;
 
@@ -206,14 +206,14 @@ exp0(Char ***vp, int ignore)
     return (p1);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 exp1(Char ***vp, int ignore)
 {
-    tcsh_number_t p1 = exp2x(vp, ignore);
+    unsigned tcsh_number_t p1 = exp2x(vp, ignore);
 
     etraci("exp1 p1", p1, vp);
     while (**vp && eq(**vp, STRand2)) {
-	tcsh_number_t p2;
+	unsigned tcsh_number_t p2;
 
 	(*vp)++;
 	p2 = compat_expr ?
@@ -230,14 +230,14 @@ exp1(Char ***vp, int ignore)
     return (p1);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 exp2x(Char ***vp, int ignore)
 {
-    tcsh_number_t p1 = exp2a(vp, ignore);
+    unsigned tcsh_number_t p1 = exp2a(vp, ignore);
 
     etraci("exp2x p1", p1, vp);
     while (**vp && eq(**vp, STRor)) {
-	tcsh_number_t p2;
+	unsigned tcsh_number_t p2;
 
 	(*vp)++;
 	p2 = compat_expr ?
@@ -253,14 +253,14 @@ exp2x(Char ***vp, int ignore)
     return (p1);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 exp2a(Char ***vp, int ignore)
 {
-    tcsh_number_t p1 = exp2b(vp, ignore);
+    unsigned tcsh_number_t p1 = exp2b(vp, ignore);
 
     etraci("exp2a p1", p1, vp);
     while (**vp && eq(**vp, STRcaret)) {
-	tcsh_number_t p2;
+	unsigned tcsh_number_t p2;
 
 	(*vp)++;
 	p2 = compat_expr ?
@@ -276,14 +276,14 @@ exp2a(Char ***vp, int ignore)
     return (p1);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 exp2b(Char ***vp, int ignore)
 {
-    tcsh_number_t p1 = exp2c(vp, ignore);
+    unsigned tcsh_number_t p1 = exp2c(vp, ignore);
 
     etraci("exp2b p1", p1, vp);
     while (**vp && eq(**vp, STRand)) {
-	tcsh_number_t p2;
+	unsigned tcsh_number_t p2;
 
 	(*vp)++;
 	p2 = compat_expr ?
@@ -299,12 +299,12 @@ exp2b(Char ***vp, int ignore)
     return (p1);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 exp2c(Char ***vp, int ignore)
 {
     Char *p1 = exp3(vp, ignore);
     Char *p2;
-    tcsh_number_t i;
+    unsigned tcsh_number_t i;
 
     cleanup_push(p1, xfree);
     etracc("exp2c p1", p1, vp);
@@ -346,7 +346,7 @@ static Char *
 exp3(Char ***vp, int ignore)
 {
     Char *p1, *p2;
-    tcsh_number_t i;
+    unsigned tcsh_number_t i;
 
     p1 = exp3a(vp, ignore);
     etracc("exp3 p1", p1, vp);
@@ -362,21 +362,58 @@ exp3(Char ***vp, int ignore)
 	etracc("exp3 p2", p2, vp);
 	if (!(ignore & TEXP_IGNORE))
 	    switch ((int)i) {
+		tcsh_number_t is;
 
 	    case GTR:
-		i = egetn(p1) > egetn(p2);
+		if ((i = egetn(p1)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p2)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = is > -(tcsh_number_t) -i;
+		else
+		    i = is > (tcsh_number_t) i;
 		break;
 
 	    case GTR | 1:
-		i = egetn(p1) >= egetn(p2);
+		if ((i = egetn(p1)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p2)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = is >= -(tcsh_number_t) -i;
+		else
+		    i = is >= (tcsh_number_t) i;
 		break;
 
 	    case LSS:
-		i = egetn(p1) < egetn(p2);
+		if ((i = egetn(p1)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p2)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = is < -(tcsh_number_t) -i;
+		else
+		    i = is < (tcsh_number_t) i;
 		break;
 
 	    case LSS | 1:
-		i = egetn(p1) <= egetn(p2);
+		if ((i = egetn(p1)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p2)) &
+		    ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = is <= -(tcsh_number_t) -i;
+		else
+		    i = is <= (tcsh_number_t) i;
 		break;
 	    }
 	cleanup_until(p1);
@@ -393,7 +430,7 @@ exp3a(Char ***vp, int ignore)
 {
     Char *p1, *p2;
     const Char *op;
-    tcsh_number_t i;
+    unsigned tcsh_number_t i;
 
     p1 = exp4(vp, ignore);
     etracc("exp3a p1", p1, vp);
@@ -421,7 +458,7 @@ static Char *
 exp4(Char ***vp, int ignore)
 {
     Char *p1, *p2;
-    tcsh_number_t i = 0;
+    unsigned tcsh_number_t i = 0;
 
     p1 = exp5(vp, ignore);
     etracc("exp4 p1", p1, vp);
@@ -458,7 +495,7 @@ static Char *
 exp5(Char ***vp, int ignore)
 {
     Char *p1, *p2;
-    tcsh_number_t i = 0;
+    unsigned tcsh_number_t i = 0;
 
     p1 = exp6(vp, ignore);
     etracc("exp5 p1", p1, vp);
@@ -482,23 +519,44 @@ exp5(Char ***vp, int ignore)
 	etracc("exp5 p2", p2, vp);
 	if (!(ignore & TEXP_IGNORE))
 	    switch (op[0]) {
+		tcsh_number_t is;
 
 	    case '*':
 		i = egetn(p1) * egetn(p2);
 		break;
 
 	    case '/':
-		i = egetn(p2);
-		if (i == 0)
+		if ((i = egetn(p2)) == 0)
 		    stderror(ERR_DIV0);
-		i = egetn(p1) / i;
+		if (i & ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p1)) ==
+		    ~(~(unsigned tcsh_number_t) 0 >> 1) &&
+		    is == -1)
+		    stderror(ERR_DIVOF);
+		if (i & ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = -(tcsh_number_t) -i / is;
+		else
+		    i /= is;
 		break;
 
 	    case '%':
-		i = egetn(p2);
-		if (i == 0)
+		if ((i = egetn(p2)) == 0)
 		    stderror(ERR_MOD0);
-		i = egetn(p1) % i;
+		if (i & ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    is = -(tcsh_number_t) -i;
+		else
+		    is = i;
+		if ((i = egetn(p1)) ==
+		    ~(~(unsigned tcsh_number_t) 0 >> 1) &&
+		    is == -1)
+		    stderror(ERR_MODOF);
+		if (i & ~(~(unsigned tcsh_number_t) 0 >> 1))
+		    i = -(tcsh_number_t) -i % is;
+		else
+		    i %= is;
 		break;
 	    }
 	cleanup_until(p1);
@@ -513,8 +571,8 @@ exp5(Char ***vp, int ignore)
 static Char *
 exp6(Char ***vp, int ignore)
 {
-    tcsh_number_t ccode;
-    tcsh_number_t i = 0;
+    unsigned tcsh_number_t ccode,
+			   i = 0;
     Char *cp;
 
     if (**vp == 0)
@@ -1022,7 +1080,7 @@ isa(Char *cp, int what)
     return (0);
 }
 
-static tcsh_number_t
+static unsigned tcsh_number_t
 egetn(const Char *cp)
 {
     if (*cp && *cp != '-' && !Isdigit(*cp))
diff --git a/sh.func.c b/sh.func.c
index a9c0dd6f..9027ddb6 100644
--- a/sh.func.c
+++ b/sh.func.c
@@ -350,7 +350,7 @@ islogin(void)
 void
 doif(Char **v, struct command *kp)
 {
-    int i;
+    unsigned tcsh_number_t i;
     Char **vv;
 
     v++;
@@ -558,7 +558,7 @@ doforeach(Char **v, struct command *c)
 void
 dowhile(Char **v, struct command *c)
 {
-    int status;
+    unsigned tcsh_number_t status;
     int again = whyles != 0 &&
 			  SEEKEQ(&whyles->w_start, &lineloc) &&
 			  whyles->w_fename == 0;
diff --git a/sh.h b/sh.h
index 19bf10d6..6fcaa8d2 100644
--- a/sh.h
+++ b/sh.h
@@ -246,9 +246,9 @@ static __inline void tcsh_ignore(intptr_t a)
 #endif /* __HP_CXD_SPP && !__hpux */
 
 #ifdef HAVE_LONG_LONG
-typedef long long tcsh_number_t;
+#define tcsh_number_t long long
 #else
-typedef long tcsh_number_t;
+#define tcsh_number_t long
 #endif
 /*
  * This macro compares the st_dev field of struct stat. On aix on ibmESA
diff --git a/sh.set.c b/sh.set.c
index ac73af9f..1e541ca1 100644
--- a/sh.set.c
+++ b/sh.set.c
@@ -45,8 +45,8 @@ static	Char		*getinx		(Char *, int *);
 static	void		 asx		(Char *, int, Char *);
 static	struct varent 	*getvx		(Char *, int);
 static	Char		*xset		(Char *, Char ***);
-static	Char		*operate	(int, Char *, Char *);
-static	void	 	 putn1		(tcsh_number_t);
+static	Char		*operate	(Char, Char *, Char *);
+static	void	 	 putn1		(unsigned tcsh_number_t);
 static	struct varent	*madrof		(Char *, struct varent *);
 static	void		 unsetv1	(struct varent *);
 static	void		 exportpath	(Char **);
@@ -491,13 +491,13 @@ xset(Char *cp, Char ***vp)
 }
 
 static Char *
-operate(int op, Char *vp, Char *p)
+operate(Char op, Char *vp, Char *p)
 {
     Char    opr[2];
     Char   *vec[5];
     Char **v = vec;
     Char  **vecp = v;
-    tcsh_number_t i;
+    unsigned tcsh_number_t i;
 
     if (op != '=') {
 	if (*vp)
@@ -519,34 +519,47 @@ operate(int op, Char *vp, Char *p)
 static Char *putp;
 
 Char *
-putn(tcsh_number_t n)
+putn(unsigned tcsh_number_t n)
 {
     Char nbuf[1024]; /* Enough even for octal */
 
     putp = nbuf;
-    if (n < 0) {
+    if (n & ~(~(unsigned tcsh_number_t) 0 >> 1)) {
 	n = -n;
 	*putp++ = '-';
     }
     putn1(n);
+#ifdef IS_ASCII
     *putp = 0;
+#endif
     return (Strsave(nbuf));
 }
 
 static void
-putn1(tcsh_number_t n)
+putn1(unsigned tcsh_number_t n)
 {
+#ifndef IS_ASCII
+    sprintf(putp, "%l"
+#ifdef HAVE_LONG_LONG
+    "l"
+#endif /* HAVE_LONG_LONG */
+    "u", n);
+#else
     if (n > 9)
 	putn1(n / 10);
     *putp++ = (Char)(n % 10 + '0');
+#endif /* !IS_ASCII */
 }
 
-tcsh_number_t
+unsigned tcsh_number_t
 getn(const Char *cp)
 {
-    tcsh_number_t n;
+    unsigned tcsh_number_t n;
     int     sign;
     int base;
+#ifndef IS_ASCII
+    char cps[2];
+#endif
 
     if (!cp)			/* PWP: extra error checking */
 	stderror(ERR_NAME | ERR_BADNUM);
@@ -566,12 +579,29 @@ getn(const Char *cp)
     else
 	base = 10;
 
+#ifndef IS_ASCII
+    cps[1] =
+#endif
     n = 0;
     while (Isdigit(*cp))
     {
+#ifndef IS_ASCII
+	unsigned tcsh_number_t ns;
+#endif
+
 	if (base == 8 && *cp >= '8')
 	    stderror(ERR_NAME | ERR_BADNUM);
+#ifndef IS_ASCII
+	cps[0] = *cp++;
+	sscanf(cps, "%l"
+#ifdef HAVE_LONG_LONG
+	"l"
+#endif /* HAVE_LONG_LONG */
+	"u", &ns);
+	n = n * base + ns;
+#else
 	n = n * base + *cp++ - '0';
+#endif /* !IS_ASCII */
     }
     if (*cp)
 	stderror(ERR_NAME | ERR_BADNUM);