diff --git a/package.json b/package.json
index 5b3dc2a..0779c6d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk-common",
-  "version": "4.11.0",
+  "version": "4.12.0",
   "description": "Common library for Eppo JavaScript SDKs (web, react native, and node)",
   "main": "dist/index.js",
   "files": [
diff --git a/src/api-endpoints.ts b/src/api-endpoints.ts
index 6d45c0c..f00eb29 100644
--- a/src/api-endpoints.ts
+++ b/src/api-endpoints.ts
@@ -3,6 +3,7 @@ import {
   UFC_ENDPOINT,
   BANDIT_ENDPOINT,
   PRECOMPUTED_FLAGS_ENDPOINT,
+  FLAG_OVERRIDES_KEY_VALIDATION_URL,
 } from './constants';
 import { IQueryParams, IQueryParamsWithSubject } from './http-client';
 
@@ -36,4 +37,8 @@ export default class ApiEndpoints {
   precomputedFlagsEndpoint(): URL {
     return this.endpoint(PRECOMPUTED_FLAGS_ENDPOINT);
   }
+
+  flagOverridesKeyValidationEndpoint(): URL {
+    return this.endpoint(FLAG_OVERRIDES_KEY_VALIDATION_URL);
+  }
 }
diff --git a/src/client/eppo-client.ts b/src/client/eppo-client.ts
index e54143b..60292b5 100644
--- a/src/client/eppo-client.ts
+++ b/src/client/eppo-client.ts
@@ -213,7 +213,8 @@ export default class EppoClient {
       return undefined;
     }
     const payload: OverridePayload = this.overrideValidator.parseOverridePayload(overridePayload);
-    await this.overrideValidator.validateKey(payload.browserExtensionKey);
+    const baseUrl = this.configurationRequestParameters?.baseUrl;
+    await this.overrideValidator.validateKey(payload.browserExtensionKey, baseUrl);
     return payload.overrides;
   }
 
@@ -222,7 +223,7 @@ export default class EppoClient {
    * to it without affecting the original EppoClient singleton. Useful for
    * applying overrides in a shared Node instance, such as a web server.
    */
-  withOverrides(overrides: Record<FlagKey, Variation>): EppoClient {
+  withOverrides(overrides: Record<FlagKey, Variation> | undefined): EppoClient {
     if (overrides && Object.keys(overrides).length) {
       const copy = shallowClone(this);
       copy.overrideStore = new MemoryOnlyConfigurationStore<Variation>();
diff --git a/src/constants.ts b/src/constants.ts
index f7c3b30..22f165e 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -9,6 +9,7 @@ export const DEFAULT_POLL_CONFIG_REQUEST_RETRIES = 7;
 export const BASE_URL = 'https://fscdn.eppo.cloud/api';
 export const UFC_ENDPOINT = '/flag-config/v1/config';
 export const BANDIT_ENDPOINT = '/flag-config/v1/bandits';
+export const FLAG_OVERRIDES_KEY_VALIDATION_URL = '/flag-overrides/v1/validate-key';
 export const PRECOMPUTED_BASE_URL = 'https://fs-edge-assignment.eppo.cloud';
 export const PRECOMPUTED_FLAGS_ENDPOINT = '/assignments';
 export const SESSION_ASSIGNMENT_CONFIG_LOADED = 'eppo-session-assignment-config-loaded';
diff --git a/src/override-validator.ts b/src/override-validator.ts
index c2a5986..77ceec5 100644
--- a/src/override-validator.ts
+++ b/src/override-validator.ts
@@ -1,17 +1,20 @@
+import ApiEndpoints from './api-endpoints';
 import { TLRUCache } from './cache/tlru-cache';
 import { Variation } from './interfaces';
 import { FlagKey } from './types';
 
 const FIVE_MINUTES_IN_MS = 5 * 3600 * 1000;
-const KEY_VALIDATION_URL = 'https://eppo.cloud/api/flag-overrides/v1/validate-key';
 
 export interface OverridePayload {
   browserExtensionKey: string;
   overrides: Record<FlagKey, Variation>;
 }
 
-export const sendValidationRequest = async (browserExtensionKey: string) => {
-  const response = await fetch(KEY_VALIDATION_URL, {
+export const sendValidationRequest = async (
+  browserExtensionKey: string,
+  validationEndpoint: string,
+) => {
+  const response = await fetch(validationEndpoint, {
     method: 'POST',
     body: JSON.stringify({
       key: browserExtensionKey,
@@ -63,11 +66,12 @@ export class OverrideValidator {
     }
   }
 
-  async validateKey(browserExtensionKey: string) {
+  async validateKey(browserExtensionKey: string, baseUrl: string | undefined) {
     if (this.validKeyCache.get(browserExtensionKey) === 'true') {
       return true;
     }
-    await sendValidationRequest(browserExtensionKey);
+    const endpoint = new ApiEndpoints({ baseUrl }).flagOverridesKeyValidationEndpoint().toString();
+    await sendValidationRequest(browserExtensionKey, endpoint);
     this.validKeyCache.set(browserExtensionKey, 'true');
   }
 }