diff --git a/dio/lib/src/adapters/io_adapter.dart b/dio/lib/src/adapters/io_adapter.dart
index 795c0fe61..50feaff6d 100644
--- a/dio/lib/src/adapters/io_adapter.dart
+++ b/dio/lib/src/adapters/io_adapter.dart
@@ -238,12 +238,12 @@ class IOHttpClientAdapter implements HttpClientAdapter {
       });
     }
 
-    responseSubscription = responseStream.listen(
+    responseSubscription = responseStream.cast<Uint8List>().listen(
       (data) {
         watchReceiveTimeout();
         // Always true if the receive timeout was not set.
         if (receiveStopwatch.elapsed <= receiveTimeout) {
-          responseSink.add(data is Uint8List ? data : Uint8List.fromList(data));
+          responseSink.add(data);
         }
       },
       onError: (error, stackTrace) {
diff --git a/dio/test/options_test.dart b/dio/test/options_test.dart
index 086fe8b34..f7d7a8464 100644
--- a/dio/test/options_test.dart
+++ b/dio/test/options_test.dart
@@ -561,8 +561,7 @@ void main() {
       when(response.reasonPhrase).thenReturn('OK');
       when(response.isRedirect).thenReturn(false);
       when(response.redirects).thenReturn([]);
-      when(response.transform(any))
-          .thenAnswer((_) => Stream<Uint8List>.empty());
+      when(response.cast()).thenAnswer((_) => Stream<Uint8List>.empty());
       return Future.value(request);
     });