diff --git a/lib/providers/camera_provider.dart b/lib/providers/camera_provider.dart
index a24a795..8646309 100644
--- a/lib/providers/camera_provider.dart
+++ b/lib/providers/camera_provider.dart
@@ -174,8 +174,8 @@
   }
 
   /// カメラリソースを解放する．
-  void disposeCamera() {
-    _stopImageStream();
+  Future<void> disposeCamera() async {
+    await _stopImageStream();
     _latestFrame = null;
     _controller?.dispose();
     _controller = null;
diff --git a/lib/services/file_service.dart b/lib/services/file_service.dart
index e169f32..ab4b257 100644
--- a/lib/services/file_service.dart
+++ b/lib/services/file_service.dart
@@ -20,23 +20,9 @@
       await directory.create(recursive: true);
     }
 
-    final yRaw = yuvData['yPlane'];
-    final uRaw = yuvData['uPlane'];
-    final vRaw = yuvData['vPlane'];
-
-    final Uint8List yPlane;
-    final Uint8List uPlane;
-    final Uint8List vPlane;
-
-    if (yRaw is Uint8List) {
-      yPlane = yRaw;
-      uPlane = uRaw as Uint8List;
-      vPlane = vRaw as Uint8List;
-    } else {
-      yPlane = Uint8List.fromList((yRaw as List).cast<int>());
-      uPlane = Uint8List.fromList((uRaw as List).cast<int>());
-      vPlane = Uint8List.fromList((vRaw as List).cast<int>());
-    }
+    final yPlane = _toUint8List(yuvData['yPlane']);
+    final uPlane = _toUint8List(yuvData['uPlane']);
+    final vPlane = _toUint8List(yuvData['vPlane']);
 
     if (yPlane.isEmpty) {
       throw Exception('YUV データが空です');
@@ -111,6 +97,11 @@
     return '${baseName}_$suffix.png';
   }
 
+  /// `dynamic` な YUV プレーンを `Uint8List` に変換する．
+  Uint8List _toUint8List(dynamic raw) => raw is Uint8List
+      ? raw
+      : Uint8List.fromList((raw as List).cast<int>());
+
   /// YUV420 を RGB に変換し PNG エンコードする（isolate 内で実行）．
   static Uint8List _convertYuvToPng(Map<String, dynamic> params) {
     final width = params['width'] as int;