diff --git a/dio/CHANGELOG.md b/dio/CHANGELOG.md
index 46ed860db..306a2b79f 100644
--- a/dio/CHANGELOG.md
+++ b/dio/CHANGELOG.md
@@ -5,7 +5,7 @@ See the [Migration Guide][] for the complete breaking changes list.**
 
 ## Unreleased
 
-*None.*
+- Improve `SyncTransformer`'s stream transform.
 
 ## 5.3.4
 
diff --git a/dio/lib/src/transformers/sync_transformer.dart b/dio/lib/src/transformers/sync_transformer.dart
index e2c6f336c..88827212d 100644
--- a/dio/lib/src/transformers/sync_transformer.dart
+++ b/dio/lib/src/transformers/sync_transformer.dart
@@ -62,9 +62,8 @@ class SyncTransformer extends Transformer {
       return responseBody;
     }
 
-    final showDownloadProgress = options.onReceiveProgress != null;
     final int totalLength;
-    if (showDownloadProgress) {
+    if (options.onReceiveProgress != null) {
       totalLength = int.parse(
         responseBody.headers[Headers.contentLengthHeader]?.first ?? '-1',
       );
@@ -72,27 +71,15 @@ class SyncTransformer extends Transformer {
       totalLength = 0;
     }
 
-    int received = 0;
-    final stream = responseBody.stream.transform<Uint8List>(
-      StreamTransformer.fromHandlers(
-        handleData: (data, sink) {
-          sink.add(data);
-          if (showDownloadProgress) {
-            received += data.length;
-            options.onReceiveProgress?.call(received, totalLength);
-          }
-        },
-      ),
-    );
-
     final streamCompleter = Completer<void>();
     int finalLength = 0;
     // Keep references to the data chunks and concatenate them later.
     final chunks = <Uint8List>[];
-    final subscription = stream.listen(
-      (chunk) {
+    final subscription = responseBody.stream.listen(
+      (Uint8List chunk) {
         finalLength += chunk.length;
         chunks.add(chunk);
+        options.onReceiveProgress?.call(finalLength, totalLength);
       },
       onError: (Object error, StackTrace stackTrace) {
         streamCompleter.completeError(error, stackTrace);