diff --git a/.changeset/eight-cooks-clap.md b/.changeset/eight-cooks-clap.md
new file mode 100644
index 000000000..1ac1e300c
--- /dev/null
+++ b/.changeset/eight-cooks-clap.md
@@ -0,0 +1,5 @@
+---
+'@lion/ajax': patch
+---
+
+fetchJSON will try to parse Response body as JSON if the content-type headers are missing, in this case it will assume JSON.
diff --git a/packages/ajax/src/Ajax.js b/packages/ajax/src/Ajax.js
index 4ea967bc5..bce865dd6 100644
--- a/packages/ajax/src/Ajax.js
+++ b/packages/ajax/src/Ajax.js
@@ -193,7 +193,10 @@ export class Ajax {
 
     /** @type {any} */
     let body = responseText;
-    if (response.headers.get('content-type')?.includes('json')) {
+    if (
+      !response.headers.get('content-type') ||
+      response.headers.get('content-type')?.includes('json')
+    ) {
       try {
         body = JSON.parse(responseText);
       } catch (error) {
diff --git a/packages/ajax/test/Ajax.test.js b/packages/ajax/test/Ajax.test.js
index 2ab260383..2c7f46d32 100644
--- a/packages/ajax/test/Ajax.test.js
+++ b/packages/ajax/test/Ajax.test.js
@@ -166,6 +166,23 @@ describe('Ajax', () => {
       expect(response.body).to.eql('!@#$');
     });
 
+    it('tries to parse Response body as JSON if the content-type header is missing', async () => {
+      fetchStub.restore();
+      fetchStub = stub(window, 'fetch');
+      fetchStub.callsFake(() => {
+        const resp = new Response('{"a":1,"b":2}', {
+          headers: {
+            // eslint-disable-next-line no-plusplus
+            'x-request-id': `${responseId++}`,
+          },
+        });
+        resp.headers.delete('content-type');
+        return Promise.resolve(resp);
+      });
+      const response = await ajax.fetchJson('/foo');
+      expect(response.body).to.eql({ a: 1, b: 2 });
+    });
+
     describe('given a request body', () => {
       it('encodes the request body as json', async () => {
         await ajax.fetchJson('/foo', { method: 'POST', body: { a: 1, b: 2 } });