diff --git a/Cachyos/Scripts/WIP/emu/cia_3ds_decryptor.py b/Cachyos/Scripts/WIP/emu/cia_3ds_decryptor.py
index 3ca77e45..c1835c77 100644
--- a/Cachyos/Scripts/WIP/emu/cia_3ds_decryptor.py
+++ b/Cachyos/Scripts/WIP/emu/cia_3ds_decryptor.py
@@ -217,14 +217,22 @@ def build_ncch_args_sequential(bin_dir: Path) -> str:
   )
 
 
-def build_ncch_args_contentid(bin_dir: Path, content_txt: Path) -> str:
+def _extract_content_ids(content_txt: Path) -> list[int]:
+  if not content_txt.exists():
+    return []
+
   content_ids = []
-  if content_txt.exists():
-    for line in content_txt.read_text(errors="replace").splitlines():
-      if "ContentId:" in line:
-        cid = line.split("ContentId:")[1].strip()[:8]
-        if cid:
-          content_ids.append(int(cid, 16))
+  for line in content_txt.read_text(errors="replace").splitlines():
+    if "ContentId:" not in line:
+      continue
+    cid = line.split("ContentId:")[1].strip()[:8]
+    if cid:
+      content_ids.append(int(cid, 16))
+  return content_ids
+
+
+def build_ncch_args_contentid(bin_dir: Path, content_txt: Path) -> str:
+  content_ids = _extract_content_ids(content_txt)
   ncch_files = sorted(bin_dir.glob("tmp.*.ncch"))
   parts = [
     f'-i "{ncch}:{i}:{content_ids[i] if i < len(content_ids) else i}"'
diff --git a/Cachyos/Scripts/WIP/emu/test_decryptor_contentid.py b/Cachyos/Scripts/WIP/emu/test_decryptor_contentid.py
new file mode 100755
index 00000000..65baf0a7
--- /dev/null
+++ b/Cachyos/Scripts/WIP/emu/test_decryptor_contentid.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+import importlib.util
+import unittest
+import sys
+from pathlib import Path
+import tempfile
+
+# Dynamically import cia_3ds_decryptor.py
+file_path = Path(__file__).parent / "cia_3ds_decryptor.py"
+spec = importlib.util.spec_from_file_location("cia_3ds_decryptor", str(file_path))
+if spec is None:
+    raise ImportError(f"Could not load {file_path}")
+decryptor = importlib.util.module_from_spec(spec)
+sys.modules["cia_3ds_decryptor"] = decryptor
+spec.loader.exec_module(decryptor)
+
+class TestDecryptorContentId(unittest.TestCase):
+    def setUp(self):
+        self.temp_dir = tempfile.TemporaryDirectory()
+        self.bin_dir = Path(self.temp_dir.name)
+        self.content_txt = self.bin_dir / "content.txt"
+
+    def tearDown(self):
+        self.temp_dir.cleanup()
+
+    def test_extract_content_ids_no_file(self):
+        self.assertEqual(decryptor._extract_content_ids(self.content_txt), [])
+
+    def test_extract_content_ids_valid_file(self):
+        content = (
+            "ContentId: 00000001\n"
+            "Some other line\n"
+            "ContentId:  00000002 \n"
+            "ContentId:\n"  # Invalid, empty after split
+        )
+        self.content_txt.write_text(content)
+        expected = [1, 2]
+        self.assertEqual(decryptor._extract_content_ids(self.content_txt), expected)
+
+    def test_build_ncch_args_contentid(self):
+        content = (
+            "ContentId: 0000000A\n"
+            "ContentId: 0000000B\n"
+        )
+        self.content_txt.write_text(content)
+
+        # Create some fake ncch files
+        (self.bin_dir / "tmp.0.ncch").touch()
+        (self.bin_dir / "tmp.1.ncch").touch()
+        (self.bin_dir / "tmp.2.ncch").touch() # More files than IDs
+
+        ncch0 = self.bin_dir / "tmp.0.ncch"
+        ncch1 = self.bin_dir / "tmp.1.ncch"
+        ncch2 = self.bin_dir / "tmp.2.ncch"
+
+        args = decryptor.build_ncch_args_contentid(self.bin_dir, self.content_txt)
+
+        # Expect content ids 10 and 11, and fallback to 2 for the last one
+        expected_parts = [
+            f'-i "{ncch0}:0:10"',
+            f'-i "{ncch1}:1:11"',
+            f'-i "{ncch2}:2:2"',
+        ]
+        self.assertEqual(args, " ".join(expected_parts))
+
+if __name__ == '__main__':
+    unittest.main()