diff --git a/libsrc/core/archive.cpp b/libsrc/core/archive.cpp
index 5454b929..d394c49c 100644
--- a/libsrc/core/archive.cpp
+++ b/libsrc/core/archive.cpp
@@ -10,24 +10,24 @@
 namespace ngcore
 {
   // clang-tidy should ignore this static object
-  static std::unique_ptr<std::map<std::string, detail::ClassArchiveInfo>> type_register;  // NOLINT
+  static std::map<std::string, detail::ClassArchiveInfo> type_register;  // NOLINT
   const detail::ClassArchiveInfo& Archive :: GetArchiveRegister(const std::string& classname)
   {
-    if(type_register == nullptr) type_register =
-                                   std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
-    return (*type_register)[classname];
+    // if(type_register == nullptr) type_register =
+    // std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
+    return (type_register)[classname];
   }
   void Archive :: SetArchiveRegister(const std::string& classname, const detail::ClassArchiveInfo& info)
   {
-    if(type_register == nullptr) type_register =
-                                   std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
-    (*type_register)[classname] = info;
+    // if(type_register == nullptr) type_register =
+    // std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
+    (type_register)[classname] = info;
   }
   bool Archive :: IsRegistered(const std::string& classname)
   {
-    if(type_register == nullptr) type_register =
-                                   std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
-    return type_register->count(classname) != 0;
+    // if(type_register == nullptr) type_register =
+    // std::make_unique<std::map<std::string, detail::ClassArchiveInfo>>();
+    return type_register.count(classname) != 0;
   }
 
 #ifdef NETGEN_PYTHON
diff --git a/libsrc/core/archive.hpp b/libsrc/core/archive.hpp
index 604a3f26..e9f28ef9 100644
--- a/libsrc/core/archive.hpp
+++ b/libsrc/core/archive.hpp
@@ -150,7 +150,8 @@ namespace ngcore
       void* (*downcaster)(const std::type_info&, void*);
 
       // Archive constructor arguments
-      std::function<void(Archive&, void*)> cargs_archiver;
+      // std::function<void(Archive&, void*)> cargs_archiver;
+      void (*cargs_archiver)(Archive&, void*);
 
 #ifdef NETGEN_PYTHON
       // std::function<pybind11::object(const std::any&)> anyToPyCaster;