diff --git a/packages/remote-config/src/client/rest_client.ts b/packages/remote-config/src/client/rest_client.ts
index 57f55f53d88..055744bbb51 100644
--- a/packages/remote-config/src/client/rest_client.ts
+++ b/packages/remote-config/src/client/rest_client.ts
@@ -76,9 +76,10 @@ export class RestClient implements RemoteConfigFetchClient {
       this.firebaseInstallations.getToken()
     ]);
 
-    const urlBase =
-      window.FIREBASE_REMOTE_CONFIG_URL_BASE ||
-      'https://firebaseremoteconfig.googleapis.com';
+    let urlBase = 'https://firebaseremoteconfig.googleapis.com';
+    if (typeof window!== 'undefined' && window.FIREBASE_REMOTE_CONFIG_URL_BASE) {
+      urlBase = window.FIREBASE_REMOTE_CONFIG_URL_BASE;
+    }
 
     const url = `${urlBase}/v1/projects/${this.projectId}/namespaces/${this.namespace}:fetch?key=${this.apiKey}`;
 
diff --git a/packages/remote-config/src/register.ts b/packages/remote-config/src/register.ts
index dda6cc544de..e262ea7df4f 100644
--- a/packages/remote-config/src/register.ts
+++ b/packages/remote-config/src/register.ts
@@ -66,6 +66,10 @@ export function registerRemoteConfig(): void {
       .getProvider('installations-internal')
       .getImmediate();
 
+    // Guards against the SDK being used when indexedDB is not available.
+    if (!isIndexedDBAvailable()) {
+      throw ERROR_FACTORY.create(ErrorCode.INDEXED_DB_UNAVAILABLE);
+    }
     // Normalizes optional inputs.
     const { projectId, apiKey, appId } = app.options;
     if (!projectId) {