diff --git a/shadowmire.py b/shadowmire.py
index 209fa50..c0df66d 100644
--- a/shadowmire.py
+++ b/shadowmire.py
@@ -23,9 +23,11 @@ logger = logging.getLogger(__name__)
 USER_AGENT = "Shadowmire (https://github.com/taoky/shadowmire)"
 
 # Note that it's suggested to use only 3 workers for PyPI.
-WORKERS = int(os.environ("SHADOWMIRE_WORKERS", "3"))
+WORKERS = int(os.environ.get("SHADOWMIRE_WORKERS", "3"))
 if WORKERS > 10:
-    logger.warning("You have set a worker value larger than 10, which is forbidden by PyPI maintainers.")
+    logger.warning(
+        "You have set a worker value larger than 10, which is forbidden by PyPI maintainers."
+    )
     logger.warning("Don't blame me if you were banned!")
 
 
@@ -342,11 +344,24 @@ class SyncBase:
         self.simple_dir.mkdir(parents=True, exist_ok=True)
         self.packages_dir.mkdir(parents=True, exist_ok=True)
         self.sync_packages = sync_packages
-        self.remote: Optional[dict[str, int]] = None
+    
+    def filter_remote_with_excludes(self, remote: dict[str, int], excludes: list[re.Pattern]) -> dict[str, int]:
+        if not excludes:
+            return remote
+        res = {}
+        for k, v in remote.items():
+            matched = False
+            for exclude in excludes:
+                if exclude.match(k):
+                    matched = True
+                    break
+            if not matched:
+                res[k] = v
+        return res
 
-    def determine_sync_plan(self, local: dict[str, int]) -> Plan:
+    def determine_sync_plan(self, local: dict[str, int], excludes: list[re.Pattern]) -> Plan:
         remote = self.fetch_remote_versions()
-        self.remote = remote
+        remote = self.filter_remote_with_excludes(remote, excludes)
         # store remote to remote.json
         with overwrite(self.basedir / "remote.json") as f:
             json.dump(remote, f)
@@ -356,6 +371,7 @@ class SyncBase:
         remote_keys = set(remote.keys())
         for i in local_keys - remote_keys:
             to_remove.append(i)
+            local_keys.remove(i)
         for i in remote_keys - local_keys:
             to_update.append(i)
         for i in local_keys:
@@ -400,7 +416,6 @@ class SyncBase:
                 sys.exit(1)
 
     def do_sync_plan(self, plan: Plan) -> None:
-        assert self.remote
         to_remove = plan.remove
         to_update = plan.update
 
@@ -580,9 +595,7 @@ class SyncPlainHTTP(SyncBase):
             package_simple_url = urljoin(self.upstream, f"/simple/{package_name}/")
             for href in current_hrefs:
                 url = urljoin(package_simple_url, href)
-                dest = (
-                    package_simple_path / href
-                ).resolve()
+                dest = (package_simple_path / href).resolve()
                 logger.info("downloading file %s -> %s", url, dest)
                 if dest.exists():
                     continue
@@ -620,6 +633,8 @@ def get_local_serial(package_simple_path: Path) -> Optional[int]:
 def main(args: argparse.Namespace) -> None:
     log_level = logging.DEBUG if os.environ.get("DEBUG") else logging.INFO
     logging.basicConfig(level=log_level)
+    logger.debug(args)
+
     basedir = Path(".")
     local_db = LocalVersionKV(basedir / "local.db", basedir / "local.json")
 
@@ -628,7 +643,7 @@ def main(args: argparse.Namespace) -> None:
             basedir=basedir, local_db=local_db, sync_packages=args.sync_packages
         )
         local = local_db.dump()
-        plan = sync.determine_sync_plan(local)
+        plan = sync.determine_sync_plan(local, args.excludes)
         # save plan for debugging
         with overwrite(basedir / "plan.json") as f:
             json.dump(plan, f, default=vars)
@@ -649,7 +664,7 @@ def main(args: argparse.Namespace) -> None:
             basedir=basedir, local_db=local_db, sync_packages=args.sync_packages
         )
         local_names = set(local_db.keys())
-        simple_dirs = set([i.name for i in (basedir / "simple").iterdir()])
+        simple_dirs = set([i.name for i in (basedir / "simple").iterdir() if i.is_dir()])
         for package_name in simple_dirs - local_names:
             sync.do_remove(package_name)
         sync.parallel_update(list(local_names))
@@ -657,14 +672,13 @@ def main(args: argparse.Namespace) -> None:
         # clean up unreferenced package files
         ref_set = set()
         for sname in simple_dirs:
-            sd = basedir / sname
-            index_html = sd / "index.html"
-            hrefs = get_existing_hrefs(index_html)
+            sd = basedir / "simple" / sname
+            hrefs = get_existing_hrefs(sd)
             for i in hrefs:
                 ref_set.add(str((sd / i).resolve()))
         for file in (basedir / "packages").glob("*/*/*/*"):
             file = file.resolve()
-            if file not in ref_set:
+            if str(file) not in ref_set:
                 logger.info("removing unreferenced %s", file)
                 file.unlink()
 
@@ -679,6 +693,9 @@ if __name__ == "__main__":
         help="Sync packages instead of just indexes",
         action="store_true",
     )
+    parser_sync.add_argument(
+        "--exclude", help="Remote package names to exclude. Regex.", nargs="*"
+    )
     parser_genlocal = subparsers.add_parser(
         "genlocal", help="(Re)generate local db and json from simple/"
     )
@@ -696,4 +713,6 @@ if __name__ == "__main__":
     if args.command is None:
         parser.print_help()
         sys.exit(1)
+    if args.command == "sync" and args.exclude:
+        args.excludes = [re.compile(i) for i in args.exclude]
     main(args)