diff --git a/src/dmaf/gcs_watcher.py b/src/dmaf/gcs_watcher.py
index b4b085c..f698278 100644
--- a/src/dmaf/gcs_watcher.py
+++ b/src/dmaf/gcs_watcher.py
@@ -96,9 +96,8 @@ def download_gcs_blob(gcs_path: str) -> Path:
     blob = bucket.blob(blob_name)
 
     suffix = Path(blob_name).suffix
-    tmp = tempfile.NamedTemporaryFile(delete=False, suffix=suffix, prefix="dmaf_gcs_")
-    blob.download_to_filename(tmp.name)
-    tmp.close()
+    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix, prefix="dmaf_gcs_") as tmp:
+        blob.download_to_filename(tmp.name)
 
     logger.debug(f"Downloaded {gcs_path} -> {tmp.name}")
     return Path(tmp.name)
diff --git a/tests/test_gcs_watcher.py b/tests/test_gcs_watcher.py
index da1c710..f7ab732 100644
--- a/tests/test_gcs_watcher.py
+++ b/tests/test_gcs_watcher.py
@@ -69,14 +69,15 @@ def test_dedup_key_is_gcs_path(self, mock_get_client):
         from PIL import Image
 
         test_img = Image.fromarray(np.zeros((100, 100, 3), dtype=np.uint8))
-        tmp = tempfile.NamedTemporaryFile(delete=False, suffix=".jpg")
-        test_img.save(tmp.name)
-        tmp.close()
+        with tempfile.NamedTemporaryFile(delete=False, suffix=".jpg") as tmp:
+            test_img.save(tmp.name)
+            temp_image_path = Path(tmp.name)
 
         # Mock blob download to copy our test image
         def fake_download(filename):
             import shutil
-            shutil.copy(tmp.name, filename)
+
+            shutil.copy(temp_image_path, filename)
 
         mock_bucket.blob.return_value.download_to_filename = fake_download
 
@@ -103,15 +104,15 @@ def fake_download(filename):
         assert result.processed == 1
 
         # Clean up our test image
-        Path(tmp.name).unlink(missing_ok=True)
+        temp_image_path.unlink(missing_ok=True)
 
     def test_local_dirs_unchanged(self, tmp_path):
         """Local directory scanning should work exactly as before."""
-        from dmaf.watcher import scan_and_process_once
-
         import numpy as np
         from PIL import Image
 
+        from dmaf.watcher import scan_and_process_once
+
         # Create a test image in local dir
         img_path = tmp_path / "test.jpg"
         test_img = Image.fromarray(np.zeros((100, 100, 3), dtype=np.uint8))
diff --git a/tests/test_watcher.py b/tests/test_watcher.py
index a72260b..620de9a 100644
--- a/tests/test_watcher.py
+++ b/tests/test_watcher.py
@@ -615,7 +615,7 @@ def test_delete_source_enabled_batch_mode(self, mock_sha256, mock_image_open, te
         mock_img = Mock(spec=Image.Image)
         mock_img_rgb = Mock()
         mock_img.convert.return_value = mock_img_rgb
-        mock_image_open.return_value = mock_img
+        mock_image_open.return_value.__enter__.return_value = mock_img
 
         mock_sha256.return_value = "test_hash"
 
@@ -656,7 +656,7 @@ def test_delete_source_disabled_batch_mode(self, mock_sha256, mock_image_open, t
         mock_img = Mock(spec=Image.Image)
         mock_img_rgb = Mock()
         mock_img.convert.return_value = mock_img_rgb
-        mock_image_open.return_value = mock_img
+        mock_image_open.return_value.__enter__.return_value = mock_img
 
         mock_sha256.return_value = "test_hash"
 
@@ -698,7 +698,7 @@ def test_delete_source_upload_failure_batch_mode(
         mock_img = Mock(spec=Image.Image)
         mock_img_rgb = Mock()
         mock_img.convert.return_value = mock_img_rgb
-        mock_image_open.return_value = mock_img
+        mock_image_open.return_value.__enter__.return_value = mock_img
 
         mock_sha256.return_value = "test_hash"