diff --git a/hm/rebuild/update-local-flakes.py b/hm/rebuild/update-local-flakes.py
index 8833695..51723f4 100755
--- a/hm/rebuild/update-local-flakes.py
+++ b/hm/rebuild/update-local-flakes.py
@@ -51,7 +51,8 @@ def process_flake(flake: str) -> None:
             "--update-input",
             dep_name,
         ]
-        subprocess.run(cmd, cwd=dir)
+        p = subprocess.run(cmd, cwd=dir)
+        p.check_returncode()
 
 
 if __name__ == "__main__":