diff --git a/modules/src/flt_arith/flt_ar2flt.c b/modules/src/flt_arith/flt_ar2flt.c
index ad1eaecb8..505f55e01 100644
--- a/modules/src/flt_arith/flt_ar2flt.c
+++ b/modules/src/flt_arith/flt_ar2flt.c
@@ -8,7 +8,7 @@
 #include "misc.h"
 #include <em_arith.h>
 
-flt_arith2flt(n, e)
+flt_arith2flt(n, e, uns)
 	register arith n;
 	register flt_arith *e;
 {
@@ -16,7 +16,7 @@ flt_arith2flt(n, e)
 	*/
 	register int i;
 
-	if (n < 0) {
+	if (!uns && n < 0) {
 		e->flt_sign = 1;
 		n = -n;
 	}
@@ -27,16 +27,11 @@ flt_arith2flt(n, e)
 		return;
 	}
 	e->flt_exp = 63;
-	if (n < 0) {
-		/* n = MINARITH */
-		n = 0x40000000;
-		while ((n << 1) > 0) n <<= 1;
-		e->flt_exp++;
-	}
+		
 	for (i = 64; i > 0 && n != 0; i--) {
 		flt_b64_sft(&(e->flt_mantissa),1);
 		e->m1 |= (n & 1) << 31;
-		n >>= 1;
+		n = (n >> 1) & ~(0x80 << 8*(sizeof(arith)-1));
 	}
 
 	if (i > 0) {
diff --git a/modules/src/flt_arith/flt_arith.3 b/modules/src/flt_arith/flt_arith.3
index 20769b0d2..983d0171c 100644
--- a/modules/src/flt_arith/flt_arith.3
+++ b/modules/src/flt_arith/flt_arith.3
@@ -61,12 +61,14 @@ extern int	flt_status;
 .B int flt_status;
 .PP
 .B #include <em_arith.h>
-.B flt_arith2flt(n, e)
+.B flt_arith2flt(n, e, uns)
 .B arith n;
 .B flt_arith *e;
+.B int uns;
 .PP
-.B arith flt_flt2arith(e)
+.B arith flt_flt2arith(e, uns)
 .B flt_arith *e;
+.B int uns;
 .PP
 .B flt_b64_sft(m, n)
 .B struct flt_mantissa *m;
@@ -184,14 +186,20 @@ converts the number
 .I n
 to the floating point format used in this package and returns the result
 in
-.IR e .
+.IR e . If the
+.I uns
+flag is set, the number
+.I n
+is regarded as an unsigned.
 .PP
 .B flt_flt2arith
 truncates the number indicated by
 .I e
 to the largest integer value smaller than or equal to the number indicated by
 .IR e .
-It returns this value.
+It returns this value. If the
+.I uns
+flag is set, the result is to be regarded as unsigned.
 .PP
 Before each operation, the
 .I flt_status
diff --git a/modules/src/flt_arith/flt_flt2ar.c b/modules/src/flt_arith/flt_flt2ar.c
index eefc51d66..ed885b80b 100644
--- a/modules/src/flt_arith/flt_flt2ar.c
+++ b/modules/src/flt_arith/flt_flt2ar.c
@@ -9,15 +9,21 @@
 #include <em_arith.h>
 
 arith
-flt_flt2arith(e)
+flt_flt2arith(e, uns)
 	register flt_arith *e;
 {
 	/*	Convert the flt_arith "n" to an arith.
 	*/
 	arith	n;
 	struct flt_mantissa a;
+	register int i;
 
+	if (uns) uns = 1;
 	flt_status = 0;
+	if (e->flt_sign && uns) {
+		flt_status = FLT_UNFL;
+		return 0;
+	}
 	if (e->flt_exp < 0) {
 		/* absolute value of result < 1.
 		   Return value only depends on sign:
@@ -25,31 +31,33 @@ flt_flt2arith(e)
 		return -e->flt_sign;
 	}
 
-	if (e->flt_exp > (8*sizeof(arith)-2)) {
+	if (e->flt_exp > 8*sizeof(arith)-2 + uns) {
 		/* probably overflow, but there is one exception:
 		*/
-		if (e->flt_sign) {
-			n = 0x80;
-			while (n << 8) n <<= 8;
-			if (e->flt_exp == 8*sizeof(arith)-1 &&
-			    e->m2 == 0 &&
-			    e->m1 == 0x80000000) {
-				/* No overflow in this case */
+		if (e->flt_sign &&
+		    e->flt_exp == 8*sizeof(arith)-1 &&
+		    e->m2 == 0 &&
+		    e->m1 == 0x80000000) {
+			/* No overflow in this case */
+			flt_status = 0;
+		}
+		else {
+			flt_status = FLT_OVFL;
+			e->flt_exp = 8*sizeof(arith)-2 + uns + e->flt_sign;
+			if (e->flt_sign) {
+				e->m1 = 0x80000000;
+				e->m2 = 0;
+			}
+			else {
+				e->m1 = 0xFFFFFFFF;
+				e->m2 = 0xFFFFFFFF;
 			}
-			else flt_status = FLT_OVFL;
-			return n;
 		}
-		n = 0x7F;
-		while ((n << 8) > 0) {
-			n <<= 8;
-			n |= 0xFF;
-		}
-		return n;
 	}
 	
 	a = e->flt_mantissa;
 	flt_b64_sft(&a, 63-e->flt_exp);
 	n = a.flt_l_32 | ((a.flt_h_32 << 16) << 16);
 	/* not << 32; this could be an undefined operation */
-	return n;
+	return e->flt_sign ? -n : n;
 }
diff --git a/modules/src/flt_arith/flt_str2fl.c b/modules/src/flt_arith/flt_str2fl.c
index f6431de4f..297432149 100644
--- a/modules/src/flt_arith/flt_str2fl.c
+++ b/modules/src/flt_arith/flt_str2fl.c
@@ -347,7 +347,7 @@ flt_ecvt(e, ndigit, decpt, sign)
 		(*decpt)++;	/* because now value in [1.0, 10.0) */
 	}
 	while (p <= pe) {
-		if (e->flt_exp >= 0) {
+		if (e->flt_exp >= 0 && e->m1 != 0) {
 			flt_arith x;
 
 			x.m2 = 0; x.flt_exp = e->flt_exp;
@@ -355,8 +355,10 @@ flt_ecvt(e, ndigit, decpt, sign)
 			x.m1 = (e->m1 >> 1) & 0x7FFFFFFF;
 			x.m1 = x.m1>>(30-e->flt_exp);
 			*p++ = (x.m1) + '0';
-			x.m1 = x.m1 << (31-e->flt_exp);
-			flt_add(e, &x, e);
+			if (x.m1) {
+				x.m1 = x.m1 << (31-e->flt_exp);
+				flt_add(e, &x, e);
+			}
 		}
 		else *p++ = '0';
 		flt_mul(e, &s10pow[1], e);