diff --git a/posthog-core/src/types.ts b/posthog-core/src/types.ts
index 53681162..d3d833d0 100644
--- a/posthog-core/src/types.ts
+++ b/posthog-core/src/types.ts
@@ -133,3 +133,5 @@ export type PostHogFlagsAndPayloadsResponse = {
 }
 
 export type JsonType = string | number | boolean | null | { [key: string]: JsonType } | Array<JsonType>
+
+export type FetchLike = (url: string, options: PostHogFetchOptions) => Promise<PostHogFetchResponse>
diff --git a/posthog-core/src/utils.ts b/posthog-core/src/utils.ts
index 8056906a..dfa715d9 100644
--- a/posthog-core/src/utils.ts
+++ b/posthog-core/src/utils.ts
@@ -1,3 +1,5 @@
+import { FetchLike } from './types'
+
 export function assert(truthyValue: any, message: string): void {
   if (!truthyValue) {
     throw new Error(message)
@@ -58,3 +60,7 @@ export function safeSetTimeout(fn: () => void, timeout: number): any {
 export const isPromise = (obj: any): obj is Promise<any> => {
   return obj && typeof obj.then === 'function'
 }
+
+export function getFetch(): FetchLike | undefined {
+  return typeof fetch !== 'undefined' ? fetch : typeof global.fetch !== 'undefined' ? global.fetch : undefined
+}
diff --git a/posthog-node/src/fetch.ts b/posthog-node/src/fetch.ts
index 52bafc22..ff70594f 100644
--- a/posthog-node/src/fetch.ts
+++ b/posthog-node/src/fetch.ts
@@ -7,14 +7,10 @@
  * See https://github.com/PostHog/posthog-js-lite/issues/127 for more info
  */
 
-import { PostHogFetchOptions, PostHogFetchResponse } from 'posthog-core/src'
+import { FetchLike, PostHogFetchOptions, PostHogFetchResponse } from 'posthog-core/src'
+import { getFetch } from 'posthog-core/src/utils'
 
-type FetchLike = (url: string, options: PostHogFetchOptions) => Promise<PostHogFetchResponse>
-
-let _fetch: FetchLike | undefined =
-  // eslint-disable-next-line @typescript-eslint/prefer-ts-expect-error
-  // @ts-ignore
-  typeof fetch !== 'undefined' ? fetch : typeof global.fetch !== 'undefined' ? global.fetch : undefined
+let _fetch: FetchLike | undefined = getFetch()
 
 if (!_fetch) {
   // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/posthog-web/CHANGELOG.md b/posthog-web/CHANGELOG.md
index 7caa150c..1246e5b2 100644
--- a/posthog-web/CHANGELOG.md
+++ b/posthog-web/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Next
 
+# 3.2.1 - 2025-01-17
+
+## Fixed
+
+1. fix: check if window and fetch are available before using on web env
+
 # 3.2.0 - 2024-12-12
 
 ## Changed
diff --git a/posthog-web/package.json b/posthog-web/package.json
index 73a1765a..9006e645 100644
--- a/posthog-web/package.json
+++ b/posthog-web/package.json
@@ -1,6 +1,6 @@
 {
   "name": "posthog-js-lite",
-  "version": "3.2.0",
+  "version": "3.2.1",
   "main": "lib/index.cjs.js",
   "module": "lib/index.esm.js",
   "types": "lib/index.d.ts",
diff --git a/posthog-web/src/context.ts b/posthog-web/src/context.ts
index 10a9de77..13ffe7d2 100644
--- a/posthog-web/src/context.ts
+++ b/posthog-web/src/context.ts
@@ -1,13 +1,14 @@
 import { utils } from '../../posthog-core'
 import { version } from '../package.json'
 
-export function getContext(window: Window): any {
+export function getContext(window: Window | undefined): any {
   let context = {}
-  if (window.navigator) {
+  if (window?.navigator) {
     const userAgent = window.navigator.userAgent
+    const osValue = os(window)
     context = {
       ...context,
-      $os: os(window),
+      ...(osValue !== undefined && { $os: osValue }),
       $browser: browser(userAgent, window.navigator.vendor, !!(window as any).opera),
       $referrer: window.document.referrer,
       $referring_domain: referringDomain(window.document.referrer),
@@ -21,6 +22,7 @@ export function getContext(window: Window): any {
       $screen_dpr: window.devicePixelRatio,
     }
   }
+
   context = {
     ...context,
     $lib: 'js',
@@ -114,7 +116,10 @@ function browserVersion(userAgent: string, vendor: string, opera: boolean): numb
   return parseFloat(matches[matches.length - 2])
 }
 
-function os(window: Window): string {
+function os(window: Window | undefined): string | undefined {
+  if (!window?.navigator) {
+    return undefined
+  }
   const a = window.navigator.userAgent
   if (/Windows/i.test(a)) {
     if (/Phone/.test(a) || /WPDesktop/.test(a)) {
@@ -134,7 +139,7 @@ function os(window: Window): string {
   } else if (/CrOS/.test(a)) {
     return 'Chrome OS'
   } else {
-    return ''
+    return undefined
   }
 }
 
diff --git a/posthog-web/src/posthog-web.ts b/posthog-web/src/posthog-web.ts
index ac4d4988..64499d46 100644
--- a/posthog-web/src/posthog-web.ts
+++ b/posthog-web/src/posthog-web.ts
@@ -8,6 +8,7 @@ import { getContext } from './context'
 import { PostHogStorage, getStorage } from './storage'
 import { version } from '../package.json'
 import { PostHogOptions } from './types'
+import { getFetch } from 'posthog-core/src/utils'
 
 export class PostHog extends PostHogCore {
   private _storage: PostHogStorage
@@ -19,7 +20,8 @@ export class PostHog extends PostHogCore {
 
     // posthog-js stores options in one object on
     this._storageKey = options?.persistence_name ? `ph_${options.persistence_name}` : `ph_${apiKey}_posthog`
-    this._storage = getStorage(options?.persistence || 'localStorage', window)
+
+    this._storage = getStorage(options?.persistence || 'localStorage', this.getWindow())
     this.setupBootstrap(options)
 
     if (options?.preloadFeatureFlags !== false) {
@@ -27,6 +29,10 @@ export class PostHog extends PostHogCore {
     }
   }
 
+  private getWindow(): Window | undefined {
+    return typeof window !== 'undefined' ? window : undefined
+  }
+
   getPersistedProperty<T>(key: PostHogPersistedProperty): T | undefined {
     if (!this._storageCache) {
       this._storageCache = JSON.parse(this._storage.getItem(this._storageKey) || '{}') || {}
@@ -50,7 +56,14 @@ export class PostHog extends PostHogCore {
   }
 
   fetch(url: string, options: PostHogFetchOptions): Promise<PostHogFetchResponse> {
-    return window.fetch(url, options)
+    const fetchFn = getFetch()
+
+    if (!fetchFn) {
+      // error will be handled by the caller (fetchWithRetry)
+      return Promise.reject(new Error('Fetch API is not available in this environment.'))
+    }
+
+    return fetchFn(url, options)
   }
 
   getLibraryId(): string {
@@ -68,7 +81,7 @@ export class PostHog extends PostHogCore {
   getCommonEventProperties(): any {
     return {
       ...super.getCommonEventProperties(),
-      ...getContext(window),
+      ...getContext(this.getWindow()),
     }
   }
 }
diff --git a/posthog-web/src/storage.ts b/posthog-web/src/storage.ts
index 5f3d8317..f9722dfe 100644
--- a/posthog-web/src/storage.ts
+++ b/posthog-web/src/storage.ts
@@ -93,9 +93,6 @@ const createStorageLike = (store: any): PostHogStorage => {
 }
 
 const checkStoreIsSupported = (storage: PostHogStorage, key = '__mplssupport__'): boolean => {
-  if (!window) {
-    return false
-  }
   try {
     const val = 'xyz'
     storage.setItem(key, val)