diff --git a/types/decimal.go b/types/decimal.go
index 9ce5cfb972..365b8c8c91 100644
--- a/types/decimal.go
+++ b/types/decimal.go
@@ -301,7 +301,7 @@ func (d Dec) QuoTruncate(d2 Dec) Dec {
 	mul := new(big.Int).Mul(d.i, precisionReuse)
 	mul.Mul(mul, precisionReuse)
 
-	quo := new(big.Int).Quo(mul, d2.i)
+	quo := mul.Quo(mul, d2.i)
 	chopped := chopPrecisionAndTruncate(quo)
 
 	if chopped.BitLen() > 255+DecimalPrecisionBits {
@@ -560,19 +560,15 @@ func (d Dec) RoundInt() Int {
 	return NewIntFromBigInt(chopPrecisionAndRoundNonMutative(d.i))
 }
 
-// similar to chopPrecisionAndRound, but always rounds down
+// chopPrecisionAndTruncate is similar to chopPrecisionAndRound,
+// but always rounds down. It does not mutate the input.
 func chopPrecisionAndTruncate(d *big.Int) *big.Int {
-	return d.Quo(d, precisionReuse)
-}
-
-func chopPrecisionAndTruncateNonMutative(d *big.Int) *big.Int {
-	tmp := new(big.Int).Set(d)
-	return chopPrecisionAndTruncate(tmp)
+	return new(big.Int).Quo(d, precisionReuse)
 }
 
 // TruncateInt64 truncates the decimals from the number and returns an int64
 func (d Dec) TruncateInt64() int64 {
-	chopped := chopPrecisionAndTruncateNonMutative(d.i)
+	chopped := chopPrecisionAndTruncate(d.i)
 	if !chopped.IsInt64() {
 		panic("Int64() out of bound")
 	}
@@ -581,12 +577,12 @@ func (d Dec) TruncateInt64() int64 {
 
 // TruncateInt truncates the decimals from the number and returns an Int
 func (d Dec) TruncateInt() Int {
-	return NewIntFromBigInt(chopPrecisionAndTruncateNonMutative(d.i))
+	return NewIntFromBigInt(chopPrecisionAndTruncate(d.i))
 }
 
 // TruncateDec truncates the decimals from the number and returns a Dec
 func (d Dec) TruncateDec() Dec {
-	return NewDecFromBigInt(chopPrecisionAndTruncateNonMutative(d.i))
+	return NewDecFromBigInt(chopPrecisionAndTruncate(d.i))
 }
 
 // Ceil returns the smallest interger value (as a decimal) that is greater than