diff --git a/pkg/encoding/bigint/bench_test.go b/pkg/encoding/bigint/bench_test.go
index 411a10b85..893be0118 100644
--- a/pkg/encoding/bigint/bench_test.go
+++ b/pkg/encoding/bigint/bench_test.go
@@ -7,9 +7,11 @@ import (
 
 func BenchmarkToPreallocatedBytes(b *testing.B) {
 	v := big.NewInt(100500)
+	vn := big.NewInt(-100500)
 	buf := make([]byte, 4)
 
 	for i := 0; i < b.N; i++ {
 		_ = ToPreallocatedBytes(v, buf[:0])
+		_ = ToPreallocatedBytes(vn, buf[:0])
 	}
 }
diff --git a/pkg/encoding/bigint/bigint.go b/pkg/encoding/bigint/bigint.go
index 4b9779e4a..8274bb684 100644
--- a/pkg/encoding/bigint/bigint.go
+++ b/pkg/encoding/bigint/bigint.go
@@ -1,6 +1,7 @@
 package bigint
 
 import (
+	"math"
 	"math/big"
 	"math/bits"
 
@@ -113,9 +114,28 @@ func ToPreallocatedBytes(n *big.Int, data []byte) []byte {
 	}
 
 	if sign < 0 {
-		n.Add(n, bigOne)
-		defer func() { n.Sub(n, bigOne) }()
-		if n.Sign() == 0 { // n == -1
+		bits := n.Bits()
+		carry := true
+		nonZero := false
+		for i := range bits {
+			if carry {
+				bits[i]--
+				carry = (bits[i] == math.MaxUint)
+			}
+			nonZero = nonZero || (bits[i] != 0)
+		}
+		defer func() {
+			var carry = true
+			for i := range bits {
+				if carry {
+					bits[i]++
+					carry = (bits[i] == 0)
+				} else {
+					break
+				}
+			}
+		}()
+		if !nonZero { // n == -1
 			return append(data[:0], 0xFF)
 		}
 	}
diff --git a/pkg/encoding/bigint/bigint_test.go b/pkg/encoding/bigint/bigint_test.go
index 79c277546..39c40d666 100644
--- a/pkg/encoding/bigint/bigint_test.go
+++ b/pkg/encoding/bigint/bigint_test.go
@@ -106,8 +106,14 @@ var testCases = []struct {
 
 func TestIntToBytes(t *testing.T) {
 	for _, tc := range testCases {
-		buf := ToBytes(big.NewInt(tc.number))
+		num := big.NewInt(tc.number)
+		var numC = *num // See #2864.
+		buf := ToBytes(num)
 		assert.Equal(t, tc.buf, buf, "error while converting %d", tc.number)
+		_ = numC.Neg(&numC)
+		_ = ToBytes(&numC)
+		_ = numC.Neg(&numC)
+		assert.Equal(t, num, &numC, "number mismatch after converting %d", tc.number)
 	}
 }