diff --git a/scripts/generate_pack.py b/scripts/generate_pack.py
index cd3598ab..2c173f3c 100644
--- a/scripts/generate_pack.py
+++ b/scripts/generate_pack.py
@@ -1230,6 +1230,7 @@ def generate_emulator_pack(
     required_only: bool = False,
     regions: list[str] | None = None,
     offline: bool | None = None,
+    platforms_dir: str | None = None,
 ) -> str | None:
     """Generate a ZIP pack for specific emulator profiles."""
     all_profiles = load_emulator_profiles(emulators_dir, skip_aliases=False)
@@ -1269,7 +1270,7 @@ def generate_emulator_pack(
     seen_hashes: set[str] = set()  # SHA1 dedup for same file, different path
     data_dir_notices: list[str] = []
     data_registry = load_data_dir_registry(
-        os.path.join(os.path.dirname(__file__), "..", "platforms")
+        platforms_dir or os.path.join(os.path.dirname(__file__), "..", "platforms")
     )
 
     with zipfile.ZipFile(zip_path, "w", zipfile.ZIP_DEFLATED) as zf:
@@ -1500,6 +1501,7 @@ def generate_system_pack(
     required_only: bool = False,
     regions: list[str] | None = None,
     offline: bool | None = None,
+    platforms_dir: str | None = None,
 ) -> str | None:
     """Generate a ZIP pack for all emulators supporting given system IDs."""
     profiles = load_emulator_profiles(emulators_dir)
@@ -1549,6 +1551,7 @@ def generate_system_pack(
         required_only=required_only,
         regions=regions,
         offline=offline,
+        platforms_dir=platforms_dir,
     )
     if result:
         # Rename to system-based name. Every dimension goes through the one
@@ -2697,6 +2700,7 @@ def main():
                 required_only=args.required_only,
                 regions=getattr(args, "regions", None),
                 offline=args.offline,
+                platforms_dir=args.platforms_dir,
             )
         if not built:
             sys.exit(1)
@@ -2717,6 +2721,7 @@ def main():
                 required_only=args.required_only,
                 regions=getattr(args, "regions", None),
                 offline=args.offline,
+                platforms_dir=args.platforms_dir,
             )
         if not built:
             sys.exit(1)
diff --git a/tests/test_verify_listing.py b/tests/test_verify_listing.py
index cbbaefce..7c3a0b47 100644
--- a/tests/test_verify_listing.py
+++ b/tests/test_verify_listing.py
@@ -71,5 +71,30 @@ class VerifyRefusesWhatAModeDoesNotRead(unittest.TestCase):
         self.assertEqual(seen, ["elsewhere"])
 
 
+class EmulatorPackReadsThePlatformsDir(unittest.TestCase):
+    def test_the_registry_comes_from_the_given_dir(self):
+        sys.path.insert(0, str(REPO_ROOT / "scripts"))
+        import generate_pack  # noqa: PLC0415
+
+        seen: list[str] = []
+
+        def registry(path: str) -> dict:
+            seen.append(str(path))
+            return {}
+
+        db = {"files": {}, "indexes": {"by_name": {}, "by_md5": {}}}
+        out = REPO_ROOT / "tmp" / "emupack-registry"
+        with mock.patch.object(generate_pack, "load_data_dir_registry", registry):
+            generate_pack.generate_emulator_pack(
+                ["handy"], str(REPO_ROOT / "emulators"), db, "bios", str(out),
+                zip_contents={}, platforms_dir="elsewhere",
+            )
+        for leftover in out.glob("*"):
+            leftover.unlink()
+        if out.exists():
+            out.rmdir()
+        self.assertEqual(seen, ["elsewhere"])
+
+
 if __name__ == "__main__":
     unittest.main()