@@ -342,7 +342,7 @@ export class FetchBackend implements HttpBackend {
     switch (request.responseType) {
       case 'json':
         // stripping the XSSI when present
-        const text = getTextDecoder(contentType).decode(binContent).replace(XSSI_PREFIX, '');
+        const text = new TextDecoder().decode(binContent).replace(XSSI_PREFIX, '');
         if (text === '') {
           return null;
         }
 
@@ -230,6 +230,16 @@ describe('FetchBackend', () => {
     expect(res.body!.data).toBe('some data');
   });
 
+  it('decodes a json response as UTF-8 regardless of its declared charset', async () => {
+    const promise = trackEvents(backend.handle(TEST_POST.clone({responseType: 'json'})));
+    fetchMock.mockFlush(HttpStatusCode.Ok, 'OK', JSON.stringify({data: 'café'}), {
+      'Content-Type': 'application/json; charset=windows-1251',
+    });
+    const events = await promise;
+    const res = events[1] as HttpResponse<{data: string}>;
+    expect(res.body!.data).toBe('café');
+  });
+
   it('handles a blank json response', async () => {
     const promise = trackEvents(backend.handle(TEST_POST.clone({responseType: 'json'})));
     fetchMock.mockFlush(HttpStatusCode.Ok, 'OK', '');
Original file line number	Diff line number	Diff line change
`@@ -342,7 +342,7 @@ export class FetchBackend implements HttpBackend {`
`342`	`342`	`switch (request.responseType) {`
`343`	`343`	`case 'json':`
`344`	`344`	`// stripping the XSSI when present`
`345`		`- const text = getTextDecoder(contentType).decode(binContent).replace(XSSI_PREFIX, '');`
	`345`	`+ const text = new TextDecoder().decode(binContent).replace(XSSI_PREFIX, '');`
`346`	`346`	`if (text === '') {`
`347`	`347`	`return null;`
`348`	`348`	`}`