diff --git a/src/UserData/UserDataStorage.hpp b/src/UserData/UserDataStorage.hpp
index a3d741c..cb99ec6 100644
--- a/src/UserData/UserDataStorage.hpp
+++ b/src/UserData/UserDataStorage.hpp
@@ -8,6 +8,7 @@
 
 namespace Porygon::UserData {
     class UserDataStorage {
+    private:
         class _internalDataStorage {
         public:
             std::unordered_map<uint32_t, UserData*> _userData;
@@ -19,6 +20,11 @@ namespace Porygon::UserData {
                 }
                 _userData.clear();
             }
+
+            _internalDataStorage() = default;
+            _internalDataStorage( const UserDataStorage& ) = delete; // non construction-copyable
+            _internalDataStorage& operator=( const UserDataStorage& ) = delete; // non copyable
+
         };
 
         static _internalDataStorage _internal;