diff --git a/src/long.ts b/src/long.ts
index 0e66c9e2..07b2b2db 100644
--- a/src/long.ts
+++ b/src/long.ts
@@ -119,42 +119,57 @@ export class Long extends BSONValue {
   /**
    * The high 32 bits as a signed value.
    */
-  high!: number;
+  high: number;
 
   /**
    * The low 32 bits as a signed value.
    */
-  low!: number;
+  low: number;
 
   /**
    * Whether unsigned or not.
    */
-  unsigned!: boolean;
+  unsigned: boolean;
 
   /**
    * Constructs a 64 bit two's-complement integer, given its low and high 32 bit values as *signed* integers.
-   *  See the from* functions below for more convenient ways of constructing Longs.
-   *
-   * Acceptable signatures are:
-   * - Long(low, high, unsigned?)
-   * - Long(bigint, unsigned?)
-   * - Long(string, unsigned?)
    *
    * @param low - The low (signed) 32 bits of the long
    * @param high - The high (signed) 32 bits of the long
    * @param unsigned - Whether unsigned or not, defaults to signed
    */
-  constructor(low: number | bigint | string = 0, high?: number | boolean, unsigned?: boolean) {
+  constructor(low: number, high?: number, unsigned?: boolean);
+  /**
+   * Constructs a 64 bit two's-complement integer, given a bigint representation.
+   *
+   * @param value - BigInt representation of the long value
+   * @param unsigned - Whether unsigned or not, defaults to signed
+   */
+  constructor(value: bigint, unsigned?: boolean);
+  /**
+   * Constructs a 64 bit two's-complement integer, given a string representation.
+   *
+   * @param value - String representation of the long value
+   * @param unsigned - Whether unsigned or not, defaults to signed
+   */
+  constructor(value: string, unsigned?: boolean);
+  constructor(
+    lowOrValue: number | bigint | string = 0,
+    highOrUnsigned?: number | boolean,
+    unsigned?: boolean
+  ) {
     super();
-    if (typeof low === 'bigint') {
-      Object.assign(this, Long.fromBigInt(low, !!high));
-    } else if (typeof low === 'string') {
-      Object.assign(this, Long.fromString(low, !!high));
-    } else {
-      this.low = low | 0;
-      this.high = (high as number) | 0;
-      this.unsigned = !!unsigned;
-    }
+    const unsignedBool = typeof highOrUnsigned === 'boolean' ? highOrUnsigned : Boolean(unsigned);
+    const high = typeof highOrUnsigned === 'number' ? highOrUnsigned : 0;
+    const res =
+      typeof lowOrValue === 'string'
+        ? Long.fromString(lowOrValue, unsignedBool)
+        : typeof lowOrValue === 'bigint'
+          ? Long.fromBigInt(lowOrValue, unsignedBool)
+          : { low: lowOrValue | 0, high: high | 0, unsigned: unsignedBool };
+    this.low = res.low;
+    this.high = res.high;
+    this.unsigned = res.unsigned;
   }
 
   static TWO_PWR_24 = Long.fromInt(TWO_PWR_24_DBL);
@@ -243,7 +258,15 @@ export class Long extends BSONValue {
    * @returns The corresponding Long value
    */
   static fromBigInt(value: bigint, unsigned?: boolean): Long {
-    return Long.fromString(value.toString(), unsigned);
+    // eslint-disable-next-line no-restricted-globals
+    const FROM_BIGINT_BIT_MASK = BigInt(0xffffffff);
+    // eslint-disable-next-line no-restricted-globals
+    const FROM_BIGINT_BIT_SHIFT = BigInt(32);
+    return new Long(
+      Number(value & FROM_BIGINT_BIT_MASK),
+      Number((value >> FROM_BIGINT_BIT_SHIFT) & FROM_BIGINT_BIT_MASK),
+      unsigned
+    );
   }
 
   /**
diff --git a/test/node/bson_type_classes.test.ts b/test/node/bson_type_classes.test.ts
index 7b4aede5..1f843eb7 100644
--- a/test/node/bson_type_classes.test.ts
+++ b/test/node/bson_type_classes.test.ts
@@ -1,6 +1,6 @@
 import { expect } from 'chai';
 import { inspect } from 'node:util';
-import { __isWeb__ } from '../register-bson';
+import { __isWeb__, __noBigInt__ } from '../register-bson';
 import {
   Binary,
   BSONRegExp,
@@ -44,7 +44,7 @@ const BSONTypeClassCtors = new Map<string, () => BSONValue>([
   ['Decimal128', () => new Decimal128('1.23')],
   ['Double', () => new Double(1.23)],
   ['Int32', () => new Int32(1)],
-  ['Long', () => new Long(1n)],
+  ['Long', () => (__noBigInt__ ? new Long(1) : new Long(1n))],
   ['MinKey', () => new MinKey()],
   ['MaxKey', () => new MaxKey()],
   ['ObjectId', () => new ObjectId('00'.repeat(12))],
diff --git a/test/node/long.test.ts b/test/node/long.test.ts
index 00377de6..85056ad3 100644
--- a/test/node/long.test.ts
+++ b/test/node/long.test.ts
@@ -1,5 +1,6 @@
 import { expect } from 'chai';
 import { Long, BSONError, __noBigInt__ } from '../register-bson';
+import { BSON_INT32_MAX, BSON_INT32_MIN } from '../../src/constants';
 
 describe('Long', function () {
   it('accepts strings in the constructor', function () {
@@ -16,14 +17,15 @@ describe('Long', function () {
   it('accepts BigInts in Long constructor', function () {
     if (__noBigInt__) {
       this.currentTest?.skip();
+    } else {
+      expect(new Long(0n).toString()).to.equal('0');
+      expect(new Long(-1n).toString()).to.equal('-1');
+      expect(new Long(-1n, true).toString()).to.equal('18446744073709551615');
+      expect(new Long(123456789123456789n).toString()).to.equal('123456789123456789');
+      expect(new Long(123456789123456789n, true).toString()).to.equal('123456789123456789');
+      expect(new Long(13835058055282163712n).toString()).to.equal('-4611686018427387904');
+      expect(new Long(13835058055282163712n, true).toString()).to.equal('13835058055282163712');
     }
-    expect(new Long(0n).toString()).to.equal('0');
-    expect(new Long(-1n).toString()).to.equal('-1');
-    expect(new Long(-1n, true).toString()).to.equal('18446744073709551615');
-    expect(new Long(123456789123456789n).toString()).to.equal('123456789123456789');
-    expect(new Long(123456789123456789n, true).toString()).to.equal('123456789123456789');
-    expect(new Long(13835058055282163712n).toString()).to.equal('-4611686018427387904');
-    expect(new Long(13835058055282163712n, true).toString()).to.equal('13835058055282163712');
   });
 
   describe('static fromExtendedJSON()', function () {
@@ -164,6 +166,52 @@ describe('Long', function () {
     });
   });
 
+  describe('static fromBigInt()', function () {
+    const inputs: [
+      name: string,
+      input: bigint,
+      unsigned: boolean | undefined,
+      expectedLong?: Long
+    ][] = [
+      ['0', BigInt('0'), false, Long.ZERO],
+      ['-0 (bigint coerces this to 0)', BigInt('-0'), false, Long.ZERO],
+      [
+        'max unsigned input',
+        BigInt(Long.MAX_UNSIGNED_VALUE.toString(10)),
+        true,
+        Long.MAX_UNSIGNED_VALUE
+      ],
+      ['max signed input', BigInt(Long.MAX_VALUE.toString(10)), false, Long.MAX_VALUE],
+      ['min signed input', BigInt(Long.MIN_VALUE.toString(10)), false, Long.MIN_VALUE],
+      [
+        'negative greater than 32 bits',
+        BigInt(-9228915101),
+        false,
+        Long.fromBits(0xd9e9ee63, 0xfffffffd)
+      ],
+      ['less than 32 bits', BigInt(245666), false, new Long(245666)],
+      ['unsigned less than 32 bits', BigInt(245666), true, new Long(245666, true)],
+      ['negative less than 32 bits', BigInt(-245666), false, new Long(-245666, -1)],
+      ['max int32', BigInt(BSON_INT32_MAX), false, new Long(BSON_INT32_MAX)],
+      ['max int32 unsigned', BigInt(BSON_INT32_MAX), true, new Long(BSON_INT32_MAX, 0, true)],
+      ['min int32', BigInt(BSON_INT32_MIN), false, new Long(BSON_INT32_MIN, -1)]
+    ];
+
+    beforeEach(function () {
+      if (__noBigInt__) {
+        this.currentTest?.skip();
+      }
+    });
+
+    for (const [testName, num, unsigned, expectedLong] of inputs) {
+      context(`when the input is ${testName}`, () => {
+        it(`should return a Long representation of the input`, () => {
+          expect(Long.fromBigInt(num, unsigned)).to.deep.equal(expectedLong);
+        });
+      });
+    }
+  });
+
   describe('static fromString()', function () {
     const successInputs: [
       name: string,
diff --git a/test/node/timestamp.test.ts b/test/node/timestamp.test.ts
index 608a217f..41ae7f4e 100644
--- a/test/node/timestamp.test.ts
+++ b/test/node/timestamp.test.ts
@@ -1,6 +1,6 @@
 import { expect } from 'chai';
 import * as BSON from '../register-bson';
-import { Timestamp } from '../register-bson';
+import { Timestamp, __noBigInt__ } from '../register-bson';
 
 describe('Timestamp', () => {
   describe('static MAX_VALUE', () => {
@@ -10,11 +10,14 @@ describe('Timestamp', () => {
   });
 
   it('should always be an unsigned value', () => {
+    let bigIntInputs: Timestamp[] = [];
+    if (!__noBigInt__) {
+      bigIntInputs = [new BSON.Timestamp(0xffffffffffn), new BSON.Timestamp(0xffffffffffffffffn)];
+    }
     const table = [
       // @ts-expect-error: Not advertized by the types, but constructs a 0 timestamp
       new BSON.Timestamp(),
-      new BSON.Timestamp(0xffffffffffn),
-      new BSON.Timestamp(0xffffffffffffffffn),
+      ...bigIntInputs,
       new BSON.Timestamp(new BSON.Long(0xffff_ffff, 0xffff_ffff, false)),
       new BSON.Timestamp(new BSON.Long(0xffff_ffff, 0xffff_ffff, true)),
       new BSON.Timestamp({ t: 0xffff_ffff, i: 0xffff_ffff }),
@@ -29,22 +32,29 @@ describe('Timestamp', () => {
   });
 
   context('output formats', () => {
-    const timestamp = new BSON.Timestamp(0xffffffffffffffffn);
+    beforeEach(function () {
+      if (__noBigInt__) {
+        this.currentTest?.skip();
+      }
+    });
 
     context('when converting toString', () => {
       it('exports an unsigned number', () => {
+        const timestamp = new BSON.Timestamp(0xffffffffffffffffn);
         expect(timestamp.toString()).to.equal('18446744073709551615');
       });
     });
 
     context('when converting toJSON', () => {
       it('exports an unsigned number', () => {
+        const timestamp = new BSON.Timestamp(0xffffffffffffffffn);
         expect(timestamp.toJSON()).to.deep.equal({ $timestamp: '18446744073709551615' });
       });
     });
 
     context('when converting toExtendedJSON', () => {
       it('exports an unsigned number', () => {
+        const timestamp = new BSON.Timestamp(0xffffffffffffffffn);
         expect(timestamp.toExtendedJSON()).to.deep.equal({
           $timestamp: { t: 4294967295, i: 4294967295 }
         });