diff --git a/builtin_bigint.go b/builtin_bigint.go
index 65a4d828..5db70844 100644
--- a/builtin_bigint.go
+++ b/builtin_bigint.go
@@ -109,8 +109,18 @@ func (v valueBigInt) baseObject(rt *Runtime) *Object {
 	return rt.getBigIntPrototype()
 }
 
-func (v valueBigInt) hash(*maphash.Hash) uint64 {
-	return v.i.Uint64()
+func (v valueBigInt) hash(hash *maphash.Hash) uint64 {
+	var sign byte
+	if v.i.Sign() < 0 {
+		sign = 0x01
+	} else {
+		sign = 0x00
+	}
+	_ = hash.WriteByte(sign)
+	_, _ = hash.Write(v.i.Bytes())
+	h := hash.Sum64()
+	hash.Reset()
+	return h
 }
 
 func toBigInt(value Value) valueBigInt {
diff --git a/map_test.go b/map_test.go
index 7d41e767..71993f42 100644
--- a/map_test.go
+++ b/map_test.go
@@ -3,6 +3,7 @@ package goja
 import (
 	"hash/maphash"
 	"math"
+	"math/big"
 	"strconv"
 	"testing"
 )
@@ -25,6 +26,8 @@ func TestMapHash(t *testing.T) {
 	testMapHashVal(floatToValue(1.2345), floatToValue(1.2345), true, t)
 	testMapHashVal(SymIterator, SymToStringTag, false, t)
 	testMapHashVal(SymIterator, SymIterator, true, t)
+	testMapHashVal(valueBigInt{big.NewInt(1)}, valueBigInt{big.NewInt(-1)}, false, t)
+	testMapHashVal(valueBigInt{big.NewInt(1)}, valueBigInt{big.NewInt(1)}, true, t)
 
 	// The following tests introduce indeterministic behaviour
 	//testMapHashVal(asciiString("Test"), asciiString("Test1"), false, t)