diff --git a/src/core.ts b/src/core.ts
index 9d90178ab..86dc31cb9 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -228,7 +228,7 @@ export abstract class APIClient {
    */
   protected defaultHeaders(opts: FinalRequestOptions): Headers {
     return {
-      Accept: 'application/json',
+      Accept: opts.stream ? 'text/event-stream' : 'application/json',
       'Content-Type': 'application/json',
       'User-Agent': this.getUserAgent(),
       ...getPlatformHeaders(),
diff --git a/tests/index.test.ts b/tests/index.test.ts
index f39571121..f8521622f 100644
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@@ -31,6 +31,11 @@ describe('instantiate client', () => {
       expect((req.headers as Headers)['x-my-default-header']).toEqual('2');
     });
 
+    test('streaming request must have Accept header set to text/event-stream', () => {
+      const { req } = client.buildRequest({ path: '/', method: 'get', stream: true });
+      expect((req.headers as Headers)['accept']).toEqual('text/event-stream');
+    });
+
     test('can ignore `undefined` and leave the default', () => {
       const { req } = client.buildRequest({
         path: '/foo',