diff --git a/tools/airdef.py b/tools/airdef.py
index 69c1b6f..7eac942 100644
--- a/tools/airdef.py
+++ b/tools/airdef.py
@@ -123,7 +123,7 @@ def mod():
     fork()
     tool = packer_path()
     if not tool.exists():
-        run([cargo(), "install", "--locked", "--no-default-features", "--root", tool.parent.parent,
+        run([cargo(), "install", "--locked", "--no-default-features", "--target-dir", FORK / "target", "--root", tool.parent.parent,
              "--path", FORK / "crates" / "cargo-horizon-mod"])
     # Invoke the pinned executable directly; PATH may contain an unrelated old packer.
     build_env = dict(os.environ)