diff --git a/app/appconfig.py b/app/appconfig.py
index 6275905..2c972bb 100644
--- a/app/appconfig.py
+++ b/app/appconfig.py
@@ -53,3 +53,4 @@ UPDATE_MIN_RATE = 1
 
 REQUEST_TIMEOUT = 60
 CACHE_DIR: str | None = None
+NO_EXTERN = False
diff --git a/app/fetch/update.py b/app/fetch/update.py
index fe2bc21..7982d12 100644
--- a/app/fetch/update.py
+++ b/app/fetch/update.py
@@ -9,6 +9,7 @@ from asyncio import Event
 
 from aiolimiter import AsyncLimiter
 
+from .. import appconfig
 from ..appconfig import UPDATE_INTERVAL, UPDATE_MIN_INTERVAL, UPDATE_MIN_RATE
 from ..appstate import state
 from ..utils import logger
@@ -57,15 +58,19 @@ async def update_loop() -> None:
         async with _rate_limit:
             logger.info("check for updates")
             try:
-                awaitables = [
-                    update_cygwin_versions(),
-                    update_gentoo_versions(),
-                    update_arch_versions(),
+                awaitables = []
+                if not appconfig.NO_EXTERN:
+                    awaitables.extend([
+                        update_cygwin_versions(),
+                        update_gentoo_versions(),
+                        update_arch_versions(),
+                    ])
+                awaitables.extend([
                     update_source(),
                     update_sourceinfos(),
                     update_build_status(),
                     update_cdx(),
-                ]
+                ])
                 await asyncio.gather(*awaitables)
                 state.ready = True
                 logger.info("done")
diff --git a/run.py b/run.py
index f40cf91..83d9b94 100755
--- a/run.py
+++ b/run.py
@@ -15,6 +15,8 @@ def main(argv: list[str]) -> int | str | None:
     parser = argparse.ArgumentParser()
     parser.add_argument("-c", "--cache", action="store_true",
                         help="use local repo cache")
+    parser.add_argument("-n", "--no-extern", action="store_true",
+                        help="only use MSYS2 data, no external repos")
     parser.add_argument("-p", "--port", type=int, default=8160,
                         help="port number")
     args = parser.parse_args()
@@ -25,6 +27,10 @@ def main(argv: list[str]) -> int | str | None:
         logger.info(f"Using cache: {repr(cache_dir)}")
         appconfig.CACHE_DIR = cache_dir
 
+    if args.no_extern:
+        logger.info("Not using external repos")
+        appconfig.NO_EXTERN = True
+
     uvicorn.run(app, host="127.0.0.1", port=args.port, log_config=None)
 
     return None