diff --git a/spec/observables/dom/ajax-spec.ts b/spec/observables/dom/ajax-spec.ts
index a3457f2d9a..41ed3a81d0 100644
--- a/spec/observables/dom/ajax-spec.ts
+++ b/spec/observables/dom/ajax-spec.ts
@@ -129,6 +129,7 @@ describe('ajax', () => {
         url: '/some/path',
         xsrfCookieName: 'foo',
         xsrfHeaderName: 'Custom-Header-Name',
+        crossDomain: false, // this is the default anyway
       };
 
       ajax(obj).subscribe();
@@ -188,12 +189,33 @@ describe('ajax', () => {
       const request = MockXMLHttpRequest.mostRecent;
 
       expect(request.url).to.equal('/some/page');
-      expect(request.requestHeaders).to.deep.equal({
-        'x-requested-with': 'XMLHttpRequest',
-      });
+      expect(request.requestHeaders).to.deep.equal({});
     });
   });
 
+  it('should not set the X-Requested-With if crossDomain is true', () => {
+    ajax({
+      url: '/test/monkey',
+      method: 'GET',
+      crossDomain: true,
+    }).subscribe();
+
+    const request = MockXMLHttpRequest.mostRecent;
+
+    expect(request.requestHeaders).to.not.have.key('x-requested-with');
+  });
+
+  it('should not set the X-Requested-With if crossDomain is not present (it defaults to true)', () => {
+    ajax({
+      url: '/test/monkey',
+      method: 'GET',
+    }).subscribe();
+
+    const request = MockXMLHttpRequest.mostRecent;
+
+    expect(request.requestHeaders).to.not.have.key('x-requested-with');
+  });
+
   it('should set the X-Requested-With if crossDomain is false', () => {
     ajax({
       url: '/test/monkey',
@@ -912,7 +934,7 @@ describe('ajax', () => {
       expect(request.method).to.equal('PATCH');
       expect(request.url).to.equal('/flibbertyJibbet');
       expect(request.requestHeaders).to.deep.equal({
-        'content-type': 'application/json;charset=utf-8',
+        'content-type': 'application/json;charset=utf-8',        
         'x-requested-with': 'XMLHttpRequest',
       });
 
@@ -1153,10 +1175,8 @@ describe('ajax', () => {
       const request = {
         async: true,
         body: undefined,
-        crossDomain: true,
-        headers: {
-          'x-requested-with': 'XMLHttpRequest',
-        },
+        crossDomain: false,
+        headers: {},
         includeUploadProgress: true,
         includeDownloadProgress: true,
         method: 'GET',
diff --git a/src/internal/ajax/ajax.ts b/src/internal/ajax/ajax.ts
index e54e2cbd4c..a24b70c4ff 100644
--- a/src/internal/ajax/ajax.ts
+++ b/src/internal/ajax/ajax.ts
@@ -276,12 +276,31 @@ const LOAD = 'load';
 
 export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
   return new Observable((destination) => {
-    // Here we're pulling off each of the configuration arguments
-    // that we don't want to add to the request information we're
-    // passing around.
-    const { queryParams, body: configuredBody, headers: configuredHeaders, ...remainingConfig } = config;
+    const requestConfig = {
+      // Default values
+      async: true,
+      crossDomain: false,
+      withCredentials: false,
+      method: 'GET',
+      timeout: 0,
+      responseType: 'json' as XMLHttpRequestResponseType,
+
+      // Override with passed user values
+      ...config,
+    } as const;
+
+    const {
+      queryParams,
+      body: configuredBody,
+      headers: configuredHeaders,
+      withCredentials,
+      xsrfCookieName,
+      xsrfHeaderName,
+      crossDomain,
+    } = requestConfig;
+
+    let url = requestConfig.url;
 
-    let { url } = remainingConfig;
     if (!url) {
       throw new TypeError('url is required');
     }
@@ -334,14 +353,13 @@ export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
     // None of this is necessary, it's only being set because it's "the thing libraries do"
     // Starting back as far as JQuery, and continuing with other libraries such as Angular 1,
     // Axios, et al.
-    if (!config.crossDomain && !('x-requested-with' in headers)) {
+    if (!crossDomain && !('x-requested-with' in headers)) {
       headers['x-requested-with'] = 'XMLHttpRequest';
     }
 
     // Allow users to provide their XSRF cookie name and the name of a custom header to use to
     // send the cookie.
-    const { withCredentials, xsrfCookieName, xsrfHeaderName } = remainingConfig;
-    if ((withCredentials || !remainingConfig.crossDomain) && xsrfCookieName && xsrfHeaderName) {
+    if ((withCredentials || !crossDomain) && xsrfCookieName && xsrfHeaderName) {
       const xsrfCookie = document?.cookie.match(new RegExp(`(^|;\\s*)(${xsrfCookieName})=([^;]*)`))?.pop() ?? '';
       if (xsrfCookie) {
         headers[xsrfHeaderName] = xsrfCookie;
@@ -353,16 +371,8 @@ export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
     const body = extractContentTypeAndMaybeSerializeBody(configuredBody, headers);
 
     const _request: AjaxRequest = {
-      // Default values
-      async: true,
-      crossDomain: true,
-      withCredentials: false,
-      method: 'GET',
-      timeout: 0,
-      responseType: 'json' as XMLHttpRequestResponseType,
-
-      // Override with passed user values
-      ...remainingConfig,
+      // Take the final configuration
+      ...requestConfig,
 
       // Set values we ensured above
       url,