diff --git a/.mypy.ini b/.mypy.ini
index a799cdd..cc3ed4a 100644
--- a/.mypy.ini
+++ b/.mypy.ini
@@ -38,3 +38,6 @@ disallow_untyped_decorators = False
 [mypy-pwnlib]
 ignore_missing_imports = True
 
+[mypy-bson]
+ignore_missing_imports = True
+
diff --git a/setup.py b/setup.py
index dd948de..e630eaa 100755
--- a/setup.py
+++ b/setup.py
@@ -9,7 +9,7 @@
 
 setuptools.setup(
     name="enochecker",
-    version="0.4.0",
+    version="0.4.1",
     author="domenukk",
     author_email="dmaier@sect.tu-berlin.de",
     description="Library to build checker scripts for EnoEngine A/D CTF Framework in Python",
diff --git a/src/enochecker/storeddict.py b/src/enochecker/storeddict.py
index d05fee6..e7eddbf 100644
--- a/src/enochecker/storeddict.py
+++ b/src/enochecker/storeddict.py
@@ -1,6 +1,5 @@
 """Backend for team_db based on a local filesystem directory."""
 
-import json
 import logging
 import os
 import threading
@@ -10,6 +9,8 @@
 from pathlib import Path
 from typing import Any, Callable, Dict, Iterator, Optional, Set
 
+import bson
+
 from .utils import base64ify, debase64ify, ensure_valid_filename
 
 logging.basicConfig(level=logging.DEBUG)
@@ -22,7 +23,7 @@
     6  # 2**6 / 10 seconds are 6.4 secs. -> That's how long the db will wait for a log
 )
 DB_PREFIX = "_store_"  # Prefix all db files will get
-DB_EXTENSION = ".json"  # Extension all db files will get
+DB_EXTENSION = ".bson"  # Extension all db files will get
 DB_LOCK_EXTENSION = ".lock"  # Extension all lock folders will get
 DB_GLOBAL_CACHE_SETTING = True
 
@@ -129,9 +130,9 @@ def _dir(self, key: str) -> str:
         """
         return os.path.join(self.path, DB_PREFIX + base64ify(key, b"+-"))
 
-    def _dir_jsonname(self, key: str) -> str:
+    def _dir_bsonname(self, key: str) -> str:
         """
-        Return the path for the json db file for this key.
+        Return the path for the bson db file for this key.
 
         See :func:`_dir`
         """
@@ -240,7 +241,7 @@ def persist(self) -> None:
             locked = self.is_locked(key) or self.ignore_locks
             if not locked:
                 self.lock(key)
-            os.remove(self._dir_jsonname(key))
+            os.remove(self._dir_bsonname(key))
             if not locked:
                 self.release(key)
             self.logger.debug(f"Deleted {key} from db {self.name}")
@@ -251,8 +252,8 @@ def persist(self) -> None:
             if not locked:
                 self.lock(key)
             try:
-                with open(self._dir_jsonname(key), "wb") as f:
-                    f.write(json.dumps(self._cache[key]).encode("utf-8"))
+                with open(self._dir_bsonname(key), "wb") as f:
+                    f.write(bson.BSON.encode({"value": self._cache[key]}))
             finally:
                 if not locked:
                     self.release(key)
@@ -272,9 +273,9 @@ def __getitem__(self, key: str) -> Any:
         if not locked:
             self.lock(key)
         try:
-            with open(self._dir_jsonname(key), "rb") as f:
-                val = json.loads(f.read().decode("utf-8"))
-        except (OSError, json.decoder.JSONDecodeError) as ex:
+            with open(self._dir_bsonname(key), "rb") as f:
+                val = bson.BSON(f.read()).decode()["value"]
+        except (OSError, bson.errors.BSONError) as ex:
             raise KeyError("Key {} not found - {}".format(key, ex))
         finally:
             if not locked:
diff --git a/tests/test_enochecker.py b/tests/test_enochecker.py
index 91b1b32..524c0cb 100644
--- a/tests/test_enochecker.py
+++ b/tests/test_enochecker.py
@@ -171,6 +171,20 @@ def test_dict():
     assert len(db) == 0
 
 
+@pytest.mark.parametrize(
+    "value", [b"binarydata", {"test": b"test", "test2": 123}, ["asd", 123, b"xyz"]]
+)
+@temp_storage_dir
+def test_storeddict_complex_types(value):
+    db = enochecker.storeddict.StoredDict(name="test", base_path=STORAGE_DIR)
+
+    db["test"] = value
+    db.persist()
+
+    db.reload()
+    assert db["test"] == value
+
+
 @temp_storage_dir
 def test_checker():
     flag = "ENOFLAG"