diff --git a/src/auth/baseexternalclient.ts b/src/auth/baseexternalclient.ts
index 81540014..1aab7123 100644
--- a/src/auth/baseexternalclient.ts
+++ b/src/auth/baseexternalclient.ts
@@ -136,9 +136,9 @@ export abstract class BaseExternalAccountClient extends AuthClient {
   private readonly stsCredential: sts.StsCredentials;
   private readonly clientAuth?: ClientAuthentication;
   private readonly workforcePoolUserProject?: string;
+  private universeDomain?: string;
   public projectId: string | null;
   public projectNumber: string | null;
-  public universeDomain?: string;
   public readonly eagerRefreshThresholdMillis: number;
   public readonly forceRefreshOnFailure: boolean;
   /**
diff --git a/test/test.baseexternalclient.ts b/test/test.baseexternalclient.ts
index 0b89e840..917ff6b4 100644
--- a/test/test.baseexternalclient.ts
+++ b/test/test.baseexternalclient.ts
@@ -70,6 +70,7 @@ describe('BaseExternalAccountClient', () => {
     credential_source: {
       file: '/var/run/secrets/goog.id/token',
     },
+    universe_domain: 'universe.domain.com',
   };
   const externalAccountOptionsWithCreds = {
     type: 'external_account',
@@ -283,26 +284,6 @@ describe('BaseExternalAccountClient', () => {
     });
   });
 
-  describe('universeDomain', () => {
-    it('should be undefined if not set', () => {
-      const client = new TestExternalAccountClient(externalAccountOptions);
-
-      assert(client.universeDomain === undefined);
-    });
-
-    it('should be set if provided', () => {
-      const universeDomain = 'universe.domain.com';
-      const options: BaseExternalAccountClientOptions = Object.assign(
-        {},
-        externalAccountOptions
-      );
-      options.universe_domain = universeDomain;
-      const client = new TestExternalAccountClient(options);
-
-      assert.equal(client.universeDomain, universeDomain);
-    });
-  });
-
   describe('getServiceAccountEmail()', () => {
     it('should return the service account email when impersonation is used', () => {
       const saEmail = 'service-1234@service-name.iam.gserviceaccount.com';