diff --git a/README.md b/README.md
index 8007d74..28b4225 100644
--- a/README.md
+++ b/README.md
@@ -45,12 +45,12 @@ If no errors were encountered, `errors` will be `null`. If errors were encounter
 
 This method is great if you want to implement custom logic based on the errors that were encountered.
 
-### `getFolderSize.loose(path, [options]): number`
+### `getFolderSize.loose(path, [options]): number | bigint`
 The `loose` method will return the folder size directly and ignore any errors it encounters, which means the returned folder size could be smaller than the real folder size.
 
 This method is great if the precise size isn't too important, for example when used only to display the folder size to the user.
 
-### `getFolderSize.strict(path, [options]): number`
+### `getFolderSize.strict(path, [options]): number | bigint`
 The `strict` method will return the folder size directly, but throw an error if it encounters any read errors.
 
 This method is great if you need a very accurate number. You will have to implement some sort of error handling to use it reliably.
@@ -63,12 +63,15 @@ Any of the three methods can also take an `options` object:
 getFolderSize(
   '/path/to/folder', 
   {
+    bigint: true,
     ignore: /pattern/,
     fs: customFS,
   }
 )
 ```
 
+If the `bigint` option is set to true, the folder size is returned as a BigInt instead of the default Number.
+
 The `ignore` option takes a regex pattern. Any file or folder with a path that matches the pattern will not be counted in the total folder size.
 
 The `fs` option allows you to pass a different filesystem handler, such as [memfs](https://github.com/streamich/memfs), that will be used to read the folder size. The filesystem handler must incorporate `lstat` and `readdir` promise functions.
diff --git a/index.js b/index.js
index f4aee12..8b56d05 100644
--- a/index.js
+++ b/index.js
@@ -6,12 +6,13 @@ import { join as joinPaths } from 'path';
  * 
  * If any errors are returned, the returned folder size is likely smaller than the real folder size.
  * 
- * @param {string} itemPath         - Path of the folder.
- * @param {object} [options]        - Options.
- * @param {object} [options.ignore] - If a file's path matches this regex object, its size is not counted.
- * @param {object} [options.fs]     - The filesystem that should be used. Uses node fs by default.
+ * @param {string}  itemPath         - Path of the folder.
+ * @param {object}  [options]        - Options.
+ * @param {boolean} [options.bigint] - Should the folder size be returned as a BigInt instead of a Number.
+ * @param {object}  [options.ignore] - If a file's path matches this regex object, its size is not counted.
+ * @param {object}  [options.fs]     - The filesystem that should be used. Uses node fs by default.
  * 
- * @returns {Promise<{size: number, errors: Array<Error> | null}>} - An object containing the size of the folder in bytes and a list of encountered errors.
+ * @returns {Promise<{size: number | bigint, errors: Array<Error> | null}>} - An object containing the size of the folder in bytes and a list of encountered errors.
  */
 export default async function getFolderSize (itemPath, options) { return await core(itemPath, options, {errors: true}) }
 
@@ -20,12 +21,13 @@ export default async function getFolderSize (itemPath, options) { return await c
  * 
  * The returned folder size might be smaller than the real folder size. It is impossible to know for sure, since errors are ignored.
  * 
- * @param {string} itemPath         - Path of the folder.
- * @param {object} [options]        - Options.
- * @param {object} [options.ignore] - If a file's path matches this regex object, its size is not counted.
- * @param {object} [options.fs]     - The filesystem that should be used. Uses node fs by default.
+ * @param {string}  itemPath         - Path of the folder.
+ * @param {object}  [options]        - Options.
+ * @param {boolean} [options.bigint] - Should the folder size be returned as a BigInt instead of a Number.
+ * @param {object}  [options.ignore] - If a file's path matches this regex object, its size is not counted.
+ * @param {object}  [options.fs]     - The filesystem that should be used. Uses node fs by default.
  * 
- * @returns {Promise<number>} - The size of the folder in bytes.
+ * @returns {Promise<number | bigint>} - The size of the folder in bytes.
  */
 getFolderSize.loose = async (itemPath, options) => await core(itemPath, options);
 
@@ -34,12 +36,13 @@ getFolderSize.loose = async (itemPath, options) => await core(itemPath, options)
  * 
  * Because errors will otherwise make this method fail, the returned folder size will always be accurate.
  * 
- * @param {string} itemPath         - Path of the folder.
- * @param {object} [options]        - Options.
- * @param {object} [options.ignore] - If a file's path matches this regex object, its size is not counted.
- * @param {object} [options.fs]     - The filesystem that should be used. Uses node fs by default.
+ * @param {string}  itemPath         - Path of the folder.
+ * @param {object}  [options]        - Options.
+ * @param {boolean} [options.bigint] - Should the folder size be returned as a BigInt instead of a Number.
+ * @param {object}  [options.ignore] - If a file's path matches this regex object, its size is not counted.
+ * @param {object}  [options.fs]     - The filesystem that should be used. Uses node fs by default.
  * 
- * @returns {Promise<number>} - The size of the folder in bytes.
+ * @returns {Promise<number | bigint>} - The size of the folder in bytes.
  */
 getFolderSize.strict = async (itemPath, options) => await core(itemPath, options, {strict: true});
 
@@ -56,7 +59,7 @@ async function core (rootItemPath, options = {}, returnType = {}) {
   async function processItem(itemPath) {
     if(options.ignore?.test(itemPath)) return;
 
-    const stats = returnType.strict ? await fs.lstat(itemPath) : await fs.lstat(itemPath).catch(error => errors.push(error));
+    const stats = returnType.strict ? await fs.lstat(itemPath, {bigint: true}) : await fs.lstat(itemPath, {bigint: true}).catch(error => errors.push(error));
     if(typeof stats !== 'object') return;
     fileSizes.set(stats.ino, stats.size);
 
@@ -71,7 +74,19 @@ async function core (rootItemPath, options = {}, returnType = {}) {
     }
   }
 
-  const folderSize = Array.from(fileSizes.values()).reduce((total, fileSize) => total + fileSize, 0);
+  let folderSize = Array.from(fileSizes.values()).reduce((total, fileSize) => total + fileSize, 0n);
+  
+  if(!options.bigint) {
+    if(folderSize > BigInt(Number.MAX_SAFE_INTEGER)){
+      const error = new RangeError('The folder size is too large to return as a Number. You can instruct this package to return a BigInt instead.');
+      if(returnType.strict){
+        throw error;
+      }else{
+        errors.push(error);
+      }
+    }
+    folderSize = Number(folderSize);
+  }
 
   if (returnType.errors) {
     return {
diff --git a/test/logic.js b/test/logic.js
index 538ada1..d1de360 100644
--- a/test/logic.js
+++ b/test/logic.js
@@ -64,6 +64,27 @@ tap.test('basic folder', async () => {
 
 });
 
+tap.test('basic folder - with bigint', async () => {
+
+  tap.test('get file sizes', async () => {
+
+    tap.equal(await callAll('/fixture/8bytes.txt', {bigint: true, fs: basicFS}), 8n, 'should return the correct file size');
+    tap.equal(await callAll('/fixture/500bytes.txt', {bigint: true, fs: basicFS}), 500n, 'should return the correct file size');
+    tap.equal(await callAll('/fixture/6000bytes.txt', {bigint: true, fs: basicFS}), 6000n, 'should return the correct file size');
+    tap.end();
+
+  });
+
+  tap.test('get folder size', async () => {
+
+    tap.equal(await callAll('/fixture', {bigint: true, fs: basicFS}), 6508n, 'should return the correct folder size');
+
+    tap.end();
+
+  });
+
+});
+
 const nestedFS = Volume.fromJSON(
   {
     './8bytes.txt': B.repeat(8),
@@ -111,6 +132,58 @@ tap.test('ignore option', async () => {
 
 });
 
+const largeFSCore = Volume.fromJSON(
+  {
+    './very.txt': B.repeat(200),
+    './large.txt': B.repeat(200),
+    './files.txt': B.repeat(200),
+  },
+  '/fixture',
+).promisesApi;
+
+const largeFS = {
+  lstat: async (itemPath, options) => {
+    const result = await largeFSCore.lstat(itemPath, options);
+    result.size = BigInt(Number.MAX_SAFE_INTEGER);
+    return result;
+  },
+  readdir: largeFSCore.readdir,
+};
+
+tap.test('handling very large filesystems', async () => {
+
+  tap.test('returning Number', async () => {
+
+    tap.type(await getFolderSize.loose('/fixture', {fs: largeFS}), 'number', 'should return Number');
+
+    tap.rejects(async () => {await getFolderSize.strict('/fixture', {fs: largeFS})}, /The folder size is too large to return as a Number. You can instruct this package to return a BigInt instead./, 'should throw appropriate error');
+
+    const { size, errors } = await getFolderSize('/fixture', {fs: largeFS});
+    tap.type(size, 'number', 'should return Number');
+    tap.type(errors, Array, 'should return Array of errors');
+    tap.equal(errors.length, 1, 'should return one error');
+    tap.equal(errors[0].message, 'The folder size is too large to return as a Number. You can instruct this package to return a BigInt instead.', 'should return appropriate error');
+
+    tap.end();
+
+  });
+
+  tap.test('returning BigInt', async () => {
+
+    tap.equal(await getFolderSize.loose('/fixture', {bigint: true, fs: largeFS}), BigInt(Number.MAX_SAFE_INTEGER) * 4n, 'should return size of 4 times max safe Number');
+
+    tap.equal(await getFolderSize.strict('/fixture', {bigint: true, fs: largeFS}), BigInt(Number.MAX_SAFE_INTEGER) * 4n, 'should return size of 4 times max safe Number');
+
+    const { size, errors } = await getFolderSize('/fixture', {bigint: true, fs: largeFS});
+    tap.equal(size, BigInt(Number.MAX_SAFE_INTEGER) * 4n, 'should return size of 4 times max safe Number');
+    tap.equal(errors, null, 'should return no errors');
+
+    tap.end();
+
+  });
+
+});
+
 const badFSCore = Volume.fromJSON(
   {
     './pass/pass.md': B.repeat(200),
@@ -126,21 +199,21 @@ const badFSCore = Volume.fromJSON(
 ).promisesApi;
 
 const badFS = {
-  lstat: async (itemPath) => {
+  lstat: async (itemPath, options) => {
     if(itemPath.includes('failFile')){
       throw Error('Nah - File');
     }else{
-      return await badFSCore.lstat(itemPath);
+      return await badFSCore.lstat(itemPath, options);
     }
   },
-  readdir: async (itemPath) => {
+  readdir: async (itemPath, options) => {
     if(itemPath.includes('failDir')){
       throw Error('Nah - Directory');
     }else{
-      return await badFSCore.readdir(itemPath);
+      return await badFSCore.readdir(itemPath, options);
     }
   }
-}
+};
 
 tap.test('error handling', async () => {