diff --git a/decimal.go b/decimal.go
index a553aa8..efdf414 100644
--- a/decimal.go
+++ b/decimal.go
@@ -1147,12 +1147,16 @@ func (z *Decimal) SetInt(x *big.Int) *Decimal {
 	// TODO(db47h) truncating x could be more efficient if z.prec > 0
 	// but small compared to the size of x.
 	z.mant = z.mant.make(int((prec + _DW - 1) / _DW)).setNat(x.Bits())
-	exp := dnorm(z.mant)
 	if z.prec == 0 {
-		// adjust precision
-		z.prec = uint32(max(len(z.mant)*_DW-int(z.mant.trailingZeroDigits()), DefaultDecimalPrec))
+		// adjust precision. z.mant is not notmalized yet. use nlz() and accept
+		// trailing zeros as part of the required precision
+		digits := int64(len(z.mant))*_DW - int64(nlz10(z.mant[len(z.mant)-1]))
+		if digits > MaxPrec {
+			digits = MaxPrec
+		}
+		z.prec = umax32(uint32(digits), DefaultDecimalPrec)
 	}
-	z.setExpAndRound(int64(len(z.mant))*_DW-exp, 0)
+	z.setExpAndRound(int64(len(z.mant))*_DW-dnorm(z.mant), 0)
 	return z
 }
 
@@ -1584,9 +1588,9 @@ func dnorm(m dec) int64 {
 	if debugDecimal && (len(m) == 0 || m[len(m)-1] == 0) {
 		panic("msw of mantissa is 0")
 	}
-	s := _DW - decDigits(uint(m[len(m)-1]))
-	// partial shift
+	s := nlz10(m[len(m)-1])
 	if s > 0 {
+		// partial shift
 		c := shl10VU(m, m, s)
 		if debugDecimal && c != 0 {
 			panic("nlz or shlVU incorrect")
diff --git a/decimal_test.go b/decimal_test.go
index 37dd3d4..ef3fecb 100644
--- a/decimal_test.go
+++ b/decimal_test.go
@@ -721,7 +721,7 @@ func TestDecimalSetInt(t *testing.T) {
 		f.SetInt(&x)
 
 		// check precision
-		n := len(strings.TrimRight(want, "0"))
+		n := len(want)
 		if n < DefaultDecimalPrec {
 			n = DefaultDecimalPrec
 		}
@@ -747,7 +747,7 @@ func TestDecimalSetRat(t *testing.T) {
 		{"-1", DefaultDecimalPrec},
 		{"1234567890", DefaultDecimalPrec},
 		{"123456789012345678901234567890", DefaultDecimalPrec},
-		{"123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890", 89},
+		{"123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890", 90},
 		{"1.2", DefaultDecimalPrec},
 		{"3.14159265", DefaultDecimalPrec},
 		// TODO(db47h) expand
diff --git a/decimal_toa.go b/decimal_toa.go
index 975dcd8..4713c66 100644
--- a/decimal_toa.go
+++ b/decimal_toa.go
@@ -346,7 +346,7 @@ func (x *Decimal) fmtP(buf []byte) []byte {
 	mant, exp := x.toa(10)
 	buf = append(buf, bytes.TrimRight(mant, "0")...)
 	buf = append(buf, 'e')
-	if x.exp >= 0 {
+	if exp >= 0 {
 		buf = append(buf, '+')
 	}
 	return strconv.AppendInt(buf, int64(exp), 10)