diff --git a/index.js b/index.js
index b3a9fc6..4b8a4c4 100644
--- a/index.js
+++ b/index.js
@@ -7,8 +7,9 @@ const isWindows = os.platform() === 'win32';
 
 function picomatch(glob, options, returnState = false) {
   // default to os.platform()
-  if (options.windows === null || options.windows === undefined) {
-    options.windows = isWindows;
+  if (options && (options.windows === null || options.windows === undefined)) {
+    // don't mutate the original options object
+    options = { ...options, windows: isWindows };
   }
   return pico(glob, options, returnState);
 }
diff --git a/lib/utils.js b/lib/utils.js
index c3ce77e..035cfe3 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -20,9 +20,11 @@ exports.removeBackslashes = str => {
 };
 
 exports.supportsLookbehinds = () => {
-  const segs = process.version.slice(1).split('.').map(Number);
-  if (segs.length === 3 && segs[0] >= 9 || (segs[0] === 8 && segs[1] >= 10)) {
-    return true;
+  if (typeof process !== 'undefined') {
+    const segs = process.version.slice(1).split('.').map(Number);
+    if (segs.length === 3 && segs[0] >= 9 || (segs[0] === 8 && segs[1] >= 10)) {
+      return true;
+    }
   }
   return false;
 };
@@ -55,9 +57,12 @@ exports.wrapOutput = (input, state = {}, options = {}) => {
 };
 
 exports.basename = (path, { windows } = {}) => {
-  if (windows) {
-    return path.replace(/[\\/]$/, '').replace(/.*[\\/]/, '');
-  } else {
-    return path.replace(/\/$/, '').replace(/.*\//, '');
+  const segs = path.split(windows ? /[\\/]/ : '/');
+  const last = segs[segs.length - 1];
+
+  if (last === '') {
+    return segs[segs.length - 2];
   }
+
+  return last;
 };
diff --git a/package.json b/package.json
index 94df1ea..f398b47 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "picomatch",
   "description": "Blazing fast and accurate glob matcher written in JavaScript, with no dependencies and full support for standard and extended Bash glob features, including braces, extglobs, POSIX brackets, and regular expressions.",
-  "version": "2.3.1",
+  "version": "3.0.0",
   "homepage": "https://github.com/micromatch/picomatch",
   "author": "Jon Schlinkert (https://github.com/jonschlinkert)",
   "funding": "https://github.com/sponsors/jonschlinkert",
diff --git a/test/dotfiles.js b/test/dotfiles.js
index e72e0f6..f90abb8 100644
--- a/test/dotfiles.js
+++ b/test/dotfiles.js
@@ -224,7 +224,7 @@ describe('dotfiles', () => {
       assert(isMatch('abc/../abc', '*/../*'));
     });
 
-    it('should not match double dots when not defined in pattern', async() => {
+    it('should not match double dots when not defined in pattern', async () => {
       assert(!isMatch('../abc', '**/*'));
       assert(!isMatch('../abc', '**/**/**'));
       assert(!isMatch('../abc', '**/**/abc'));
@@ -291,7 +291,7 @@ describe('dotfiles', () => {
       assert(!isMatch('abc/abc/..', 'abc/*/**/*', { strictSlashes: true }));
     });
 
-    it('should not match single exclusive dots when not defined in pattern', async() => {
+    it('should not match single exclusive dots when not defined in pattern', async () => {
       assert(!isMatch('.', '**'));
       assert(!isMatch('abc/./abc', '**'));
       assert(!isMatch('abc/abc/.', '**'));
diff --git a/test/special-characters.js b/test/special-characters.js
index f9c4054..c6958a5 100644
--- a/test/special-characters.js
+++ b/test/special-characters.js
@@ -226,7 +226,7 @@ describe('special characters', () => {
       assert(isMatch('foo(bar)baz', 'foo*baz'));
     });
 
-    it('should match literal parens with brackets', async() => {
+    it('should match literal parens with brackets', async () => {
       assert(isMatch('foo(bar)baz', 'foo[bar()]+baz'));
     });