diff --git a/github-release/tunasync/github-release.py b/github-release/tunasync/github-release.py
index 1953310..c9ad1a2 100644
--- a/github-release/tunasync/github-release.py
+++ b/github-release/tunasync/github-release.py
@@ -2,6 +2,7 @@
 
 import os
 import sys
+import tempfile
 import threading
 import traceback
 import queue
@@ -74,25 +75,29 @@ def github_get(*args, **kwargs):
     return requests.get(*args, **kwargs)
 
 
-def do_download(remote_url: str, dst_file: Path, remote_ts: float):
-    tmpfile = dst_file.parent / (dst_file.name + '.downloading')
-    try:
-        # NOTE the stream=True parameter below
-        with github_get(remote_url, stream=True) as r:
-            r.raise_for_status()
-            with open(tmpfile, 'wb') as f:
+def do_download(remote_url: str, dst_file: Path, remote_ts: float, remote_size: int):
+    # NOTE the stream=True parameter below
+    with github_get(remote_url, stream=True) as r:
+        r.raise_for_status()
+        tmp_dst_file = None
+        try:
+            with tempfile.NamedTemporaryFile(prefix="." + dst_file.name + ".", suffix=".tmp", dir=dst_file.parent, delete=False) as f:
+                tmp_dst_file = Path(f.name)
                 for chunk in r.iter_content(chunk_size=1024**2):
                     if chunk:  # filter out keep-alive new chunks
                         f.write(chunk)
                         # f.flush()
-            os.utime(tmpfile, (remote_ts, remote_ts))
-    except Exception as e:
-        raise
-    else:
-        tmpfile.rename(dst_file)
-    finally:
-        if tmpfile.is_file():
-            tmpfile.unlink()
+            # check for downloaded size
+            downloaded_size = tmp_dst_file.stat().st_size
+            if remote_size is not None and downloaded_size != remote_size:
+                raise ValueError(f'File {dst_file.as_posix()} size mismatch: downloaded {downloaded_size} bytes, expected {remote_size} bytes')
+            os.utime(tmp_dst_file, (remote_ts, remote_ts))
+            tmp_dst_file.chmod(0o644)
+            tmp_dst_file.replace(dst_file)
+        finally:
+            if tmp_dst_file is not None:
+                if tmp_dst_file.is_file():
+                    tmp_dst_file.unlink()
 
 
 def downloading_worker(q):
@@ -101,7 +106,7 @@ def downloading_worker(q):
         if item is None:
             break
 
-        url, dst_file, working_dir, updated = item
+        url, dst_file, working_dir, updated, remote_size = item
 
         print("downloading", url, "to",
               dst_file.relative_to(working_dir), flush=True)
@@ -159,12 +164,14 @@ def download(release, release_dir, tarball=False):
                 release['published_at'], '%Y-%m-%dT%H:%M:%SZ').timestamp()
             dst_file = release_dir / 'repo-snapshot.tar.gz'
             remote_filelist.append(dst_file.relative_to(working_dir))
+            # no size information, use None to skip size check
+            remote_size = None
 
             if dst_file.is_file():
                 print("skipping", dst_file.relative_to(working_dir), flush=True)
             else:
                 dst_file.parent.mkdir(parents=True, exist_ok=True)
-                task_queue.put((url, dst_file, working_dir, updated))
+                task_queue.put((url, dst_file, working_dir, updated, remote_size))
 
         for asset in release['assets']:
             url = asset['browser_download_url']
@@ -172,7 +179,8 @@ def download(release, release_dir, tarball=False):
                 asset['updated_at'], '%Y-%m-%dT%H:%M:%SZ').timestamp()
             dst_file = release_dir / ensure_safe_name(asset['name'])
             remote_filelist.append(dst_file.relative_to(working_dir))
-            total_size += asset['size']
+            remote_size = asset['size']
+            total_size += remote_size
 
             if dst_file.is_file():
                 if args.fast_skip:
@@ -186,14 +194,14 @@ def download(release, release_dir, tarball=False):
                     # print(f"{local_filesize} vs {asset['size']}")
                     # print(f"{local_mtime} vs {updated}")
                     if local_mtime > updated or \
-                            asset['size'] == local_filesize and local_mtime == updated:
+                            remote_size == local_filesize and local_mtime == updated:
                         print("skipping", dst_file.relative_to(
                             working_dir), flush=True)
                         continue
             else:
                 dst_file.parent.mkdir(parents=True, exist_ok=True)
 
-            task_queue.put((url, dst_file, working_dir, updated))
+            task_queue.put((url, dst_file, working_dir, updated, remote_size))
 
     def link_latest(name, repo_dir):
         try: