diff --git a/packages/flutter_test/lib/src/_goldens_io.dart b/packages/flutter_test/lib/src/_goldens_io.dart
index 28009b8d827..8fe478c8366 100644
--- a/packages/flutter_test/lib/src/_goldens_io.dart
+++ b/packages/flutter_test/lib/src/_goldens_io.dart
@@ -188,10 +188,12 @@ Future<ComparisonResult> compareLists(List<int>? test, List<int>? master) async
 
   final Codec testImageCodec = await instantiateImageCodec(Uint8List.fromList(test));
   final Image testImage = (await testImageCodec.getNextFrame()).image;
+  testImageCodec.dispose();
   final ByteData? testImageRgba = await testImage.toByteData();
 
   final Codec masterImageCodec = await instantiateImageCodec(Uint8List.fromList(master));
   final Image masterImage = (await masterImageCodec.getNextFrame()).image;
+  masterImageCodec.dispose();
   final ByteData? masterImageRgba = await masterImage.toByteData();
 
   final int width = testImage.width;