diff --git a/src/hwpx/data/Skeleton.hwpx b/src/hwpx/data/Skeleton.hwpx
index 7b24a05..762711a 100644
Binary files a/src/hwpx/data/Skeleton.hwpx and b/src/hwpx/data/Skeleton.hwpx differ
diff --git a/tests/test_skeleton_template_ids.py b/tests/test_skeleton_template_ids.py
new file mode 100644
index 0000000..11bc852
--- /dev/null
+++ b/tests/test_skeleton_template_ids.py
@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+import re
+import zipfile
+from importlib.resources import files
+
+
+def test_skeleton_template_ids_fit_in_signed_int32() -> None:
+    """The bundled HWPX skeleton (`hwpx/data/Skeleton.hwpx`) is the seed
+    used by ``HwpxDocument.new()``. Every numeric ``id`` inside it must
+    fit in signed int32 so consumers that parse ids as ``int`` see a
+    non-negative value."""
+
+    skeleton = files("hwpx.data") / "Skeleton.hwpx"
+    with zipfile.ZipFile(skeleton.open("rb")) as zf:
+        for name in zf.namelist():
+            if not name.endswith(".xml"):
+                continue
+            data = zf.read(name).decode("utf-8")
+            for match in re.finditer(r'\sid="(-?\d+)"', data):
+                value = int(match.group(1))
+                assert 0 <= value < 2**31, (
+                    f"{name} contains id={value} (0x{value:x}); "
+                    "Skeleton.hwpx values must stay in [0, 2^31)"
+                )