diff --git a/3rd/cjson/src/cJSONw.cpp b/3rd/cjson/src/cJSONw.cpp
index 61657213..061d7f1c 100644
--- a/3rd/cjson/src/cJSONw.cpp
+++ b/3rd/cjson/src/cJSONw.cpp
@@ -52,12 +52,12 @@ static PyVar convert_cjson_to_list(const cJSON * const item, VM* vm){
 }
 
 static PyVar convert_cjson_to_dict(const cJSON* const item, VM* vm){
-    Dict output(vm);
+    Dict output;
     cJSON *child = item->child;
     while(child != NULL){
         const char* key = child->string;
         const cJSON *child_value = cJSON_GetObjectItemCaseSensitive(item, key);
-        output.set(VAR(key), convert_cjson_to_python_object(child_value, vm));
+        output.set(vm, VAR(key), convert_cjson_to_python_object(child_value, vm));
         child = child->next;
     }
     return VAR(std::move(output));
diff --git a/include/pocketpy/dict.h b/include/pocketpy/dict.h
index 120e4cd3..46647722 100644
--- a/include/pocketpy/dict.h
+++ b/include/pocketpy/dict.h
@@ -23,7 +23,6 @@ struct Dict{
     static_assert(sizeof(Item) * __Capacity <= 128);
     static_assert(sizeof(ItemNode) * __Capacity <= 64);
 
-    VM* vm;
     int _capacity;
     int _mask;
     int _size;
@@ -33,7 +32,7 @@ struct Dict{
     Item* _items;
     ItemNode* _nodes;       // for order preserving
 
-    Dict(VM* vm);
+    Dict();
     Dict(Dict&& other);
     Dict(const Dict& other);
     Dict& operator=(const Dict&) = delete;
@@ -41,17 +40,17 @@ struct Dict{
 
     int size() const { return _size; }
 
-    void _probe_0(PyVar key, bool& ok, int& i) const;
-    void _probe_1(PyVar key, bool& ok, int& i) const;
+    void _probe_0(VM* vm, PyVar key, bool& ok, int& i) const;
+    void _probe_1(VM* vm, PyVar key, bool& ok, int& i) const;
 
-    void set(PyVar key, PyVar val);
-    void _rehash();
+    void set(VM* vm, PyVar key, PyVar val);
+    void _rehash(VM* vm);
 
-    PyVar try_get(PyVar key) const;
+    PyVar try_get(VM* vm, PyVar key) const;
 
-    bool contains(PyVar key) const;
-    bool erase(PyVar key);
-    void update(const Dict& other);
+    bool contains(VM* vm, PyVar key) const;
+    bool erase(VM* vm, PyVar key);
+    void update(VM* vm, const Dict& other);
 
     template<typename __Func>
     void apply(__Func f) const {
diff --git a/src/ceval.cpp b/src/ceval.cpp
index d7ed2d4d..fb711af9 100644
--- a/src/ceval.cpp
+++ b/src/ceval.cpp
@@ -393,7 +393,7 @@ __NEXT_STEP:
     } DISPATCH()
     case OP_BUILD_DICT:{
         if(byte.arg == 0){
-            PUSH(VAR(Dict(this)));
+            PUSH(VAR(Dict()));
             DISPATCH()
         }
         PyVar _0 = VAR(STACK_VIEW(byte.arg).to_list());
@@ -439,7 +439,7 @@ __NEXT_STEP:
     } DISPATCH()
     case OP_BUILD_DICT_UNPACK: {
         auto _lock = heap.gc_scope_lock();
-        Dict dict(this);
+        Dict dict;
         __unpack_as_dict(STACK_VIEW(byte.arg), dict);
         STACK_SHRINK(byte.arg);
         PyVar _0 = VAR(std::move(dict));
@@ -769,7 +769,7 @@ __NEXT_STEP:
     case OP_DICT_ADD: {
         PyVar _0 = POPX();
         const Tuple& t = PK_OBJ_GET(Tuple, _0);
-        PK_OBJ_GET(Dict, SECOND()).set(t[0], t[1]);
+        PK_OBJ_GET(Dict, SECOND()).set(this, t[0], t[1]);
     } DISPATCH()
     case OP_SET_ADD:{
         PyVar _0 = POPX();
diff --git a/src/csv.cpp b/src/csv.cpp
index 68e44dca..e7f4c755 100644
--- a/src/csv.cpp
+++ b/src/csv.cpp
@@ -80,9 +80,9 @@ __NEXT_LINE:
             if(row.size() != header.size()){
                 vm->ValueError("row.size() != header.size()");
             }
-            Dict row_dict(vm);
+            Dict row_dict;
             for(int j=0; j<header.size(); j++){
-                row_dict.set(header[j], row[j]);
+                row_dict.set(vm, header[j], row[j]);
             }
             new_ret.push_back(VAR(std::move(row_dict)));
         }
diff --git a/src/dataclasses.cpp b/src/dataclasses.cpp
index 842b5873..5c96af87 100644
--- a/src/dataclasses.cpp
+++ b/src/dataclasses.cpp
@@ -105,9 +105,9 @@ void add_module_dataclasses(VM* vm){
     vm->bind_func(mod, "asdict", 1, [](VM* vm, ArgsView args){
         const auto& fields = vm->_tp_info(args[0])->annotated_fields;
         const NameDict& obj_d = args[0]->attr();
-        Dict d(vm);
+        Dict d;
         for(StrName field: fields){
-            d.set(VAR(field.sv()), obj_d[field]);
+            d.set(vm, VAR(field.sv()), obj_d[field]);
         }
         return VAR(std::move(d));
     });
diff --git a/src/dict.cpp b/src/dict.cpp
index dbe63ce1..1e37632e 100644
--- a/src/dict.cpp
+++ b/src/dict.cpp
@@ -2,7 +2,7 @@
 
 namespace pkpy{
 
-    Dict::Dict(VM* vm): vm(vm), _capacity(__Capacity),
+    Dict::Dict(): _capacity(__Capacity),
             _mask(__Capacity-1),
             _size(0), _critical_size(__Capacity*__LoadFactor+0.5f), _head_idx(-1), _tail_idx(-1){
         _items = (Item*)pool128_alloc(_capacity * sizeof(Item));
@@ -12,7 +12,6 @@ namespace pkpy{
     }
 
     Dict::Dict(Dict&& other){
-        vm = other.vm;
         _capacity = other._capacity;
         _mask = other._mask;
         _size = other._size;
@@ -26,7 +25,6 @@ namespace pkpy{
     }
 
     Dict::Dict(const Dict& other){
-        vm = other.vm;
         _capacity = other._capacity;
         _mask = other._mask;
         _size = other._size;
@@ -39,11 +37,11 @@ namespace pkpy{
         memcpy(_nodes, other._nodes, _capacity * sizeof(ItemNode));
     }
 
-    void Dict::set(PyVar key, PyVar val){
+    void Dict::set(VM* vm, PyVar key, PyVar val){
         // do possible rehash
-        if(_size+1 > _critical_size) _rehash();
+        if(_size+1 > _critical_size) _rehash(vm);
         bool ok; int i;
-        _probe_1(key, ok, i);
+        _probe_1(vm, key, ok, i);
         if(!ok) {
             _size++;
             _items[i].first = key;
@@ -61,7 +59,7 @@ namespace pkpy{
         _items[i].second = val;
     }
 
-    void Dict::_rehash(){
+    void Dict::_rehash(VM* vm){
         Item* old_items = _items;
         ItemNode* old_nodes = _nodes;
         int old_head_idx = _head_idx;
@@ -81,7 +79,7 @@ namespace pkpy{
         // copy old items to new dict
         int i = old_head_idx;
         while(i != -1){
-            set(old_items[i].first, old_items[i].second);
+            set(vm, old_items[i].first, old_items[i].second);
             i = old_nodes[i].next;
         }
         pool128_dealloc(old_items);
@@ -89,22 +87,22 @@ namespace pkpy{
     }
 
 
-    PyVar Dict::try_get(PyVar key) const{
+    PyVar Dict::try_get(VM* vm, PyVar key) const{
         bool ok; int i;
-        _probe_0(key, ok, i);
+        _probe_0(vm, key, ok, i);
         if(!ok) return nullptr;
         return _items[i].second;
     }
 
-    bool Dict::contains(PyVar key) const{
+    bool Dict::contains(VM* vm, PyVar key) const{
         bool ok; int i;
-        _probe_0(key, ok, i);
+        _probe_0(vm, key, ok, i);
         return ok;
     }
 
-    bool Dict::erase(PyVar key){
+    bool Dict::erase(VM* vm, PyVar key){
         bool ok; int i;
-        _probe_0(key, ok, i);
+        _probe_0(vm, key, ok, i);
         if(!ok) return false;
         _items[i].first = nullptr;
         // _items[i].second = PY_DELETED_SLOT;  // do not change .second if it is not NULL, it means the slot is occupied by a deleted item
@@ -130,8 +128,8 @@ namespace pkpy{
         return true;
     }
 
-    void Dict::update(const Dict& other){
-        other.apply([&](PyVar k, PyVar v){ set(k, v); });
+    void Dict::update(VM* vm, const Dict& other){
+        other.apply([&](PyVar k, PyVar v){ set(vm, k, v); });
     }
 
     Tuple Dict::keys() const{
diff --git a/src/pocketpy.cpp b/src/pocketpy.cpp
index e590c29d..34607bcd 100644
--- a/src/pocketpy.cpp
+++ b/src/pocketpy.cpp
@@ -1264,7 +1264,7 @@ void __init_builtins(VM* _vm) {
     // tp_dict
     _vm->bind_func(VM::tp_dict, __new__, -1, [](VM* vm, ArgsView args){
         Type cls_t = PK_OBJ_GET(Type, args[0]);
-        return vm->new_object<Dict>(cls_t, vm);
+        return vm->new_object<Dict>(cls_t);
     });
 
     _vm->bind_func(VM::tp_dict, __init__, -1, [](VM* vm, ArgsView args){
@@ -1274,7 +1274,7 @@ void __init_builtins(VM* _vm) {
             Dict& self = PK_OBJ_GET(Dict, args[0]);
             if(is_type(args[1], vm->tp_dict)){
                 Dict& other = CAST(Dict&, args[1]);
-                self.update(other);
+                self.update(vm, other);
                 return vm->None;
             }
             if(is_type(args[1], vm->tp_list)){
@@ -1285,7 +1285,7 @@ void __init_builtins(VM* _vm) {
                         vm->ValueError("dict() takes a list of tuples (key, value)");
                         return vm->None;
                     }
-                    self.set(t[0], t[1]);
+                    self.set(vm, t[0], t[1]);
                 }
                 return vm->None;
             }
@@ -1301,7 +1301,7 @@ void __init_builtins(VM* _vm) {
 
     _vm->bind__getitem__(VM::tp_dict, [](VM* vm, PyVar _0, PyVar _1) {
         Dict& self = PK_OBJ_GET(Dict, _0);
-        PyVar ret = self.try_get(_1);
+        PyVar ret = self.try_get(vm, _1);
         if(ret == nullptr){
             // try __missing__
             PyVar self;
@@ -1316,12 +1316,12 @@ void __init_builtins(VM* _vm) {
 
     _vm->bind__setitem__(VM::tp_dict, [](VM* vm, PyVar _0, PyVar _1, PyVar _2) {
         Dict& self = _CAST(Dict&, _0);
-        self.set(_1, _2);
+        self.set(vm, _1, _2);
     });
 
     _vm->bind__delitem__(VM::tp_dict, [](VM* vm, PyVar _0, PyVar _1) {
         Dict& self = _CAST(Dict&, _0);
-        bool ok = self.erase(_1);
+        bool ok = self.erase(vm, _1);
         if(!ok) vm->KeyError(_1);
     });
 
@@ -1331,20 +1331,20 @@ void __init_builtins(VM* _vm) {
             return vm->None;
         }
         Dict& self = _CAST(Dict&, args[0]);
-        PyVar value = self.try_get(args[1]);
+        PyVar value = self.try_get(vm, args[1]);
         if(value == nullptr){
             if(args.size() == 2) vm->KeyError(args[1]);
             if(args.size() == 3){
                 return args[2];
             }
         }
-        self.erase(args[1]);
+        self.erase(vm, args[1]);
         return value;
     });
 
     _vm->bind__contains__(VM::tp_dict, [](VM* vm, PyVar _0, PyVar _1) {
         Dict& self = _CAST(Dict&, _0);
-        return VAR(self.contains(_1));
+        return VAR(self.contains(vm, _1));
     });
 
     _vm->bind__iter__(VM::tp_dict, [](VM* vm, PyVar _0) {
@@ -1355,11 +1355,11 @@ void __init_builtins(VM* _vm) {
     _vm->bind_func(VM::tp_dict, "get", -1, [](VM* vm, ArgsView args) {
         Dict& self = _CAST(Dict&, args[0]);
         if(args.size() == 1+1){
-            PyVar ret = self.try_get(args[1]);
+            PyVar ret = self.try_get(vm, args[1]);
             if(ret != nullptr) return ret;
             return vm->None;
         }else if(args.size() == 1+2){
-            PyVar ret = self.try_get(args[1]);
+            PyVar ret = self.try_get(vm, args[1]);
             if(ret != nullptr) return ret;
             return args[2];
         }
@@ -1384,7 +1384,7 @@ void __init_builtins(VM* _vm) {
     _vm->bind_func(VM::tp_dict, "update", 2, [](VM* vm, ArgsView args) {
         Dict& self = _CAST(Dict&, args[0]);
         const Dict& other = CAST(Dict&, args[1]);
-        self.update(other);
+        self.update(vm, other);
         return vm->None;
     });
 
@@ -1424,7 +1424,7 @@ void __init_builtins(VM* _vm) {
         for(int i=0; i<self._capacity; i++){
             auto item = self._items[i];
             if(item.first == nullptr) continue;
-            PyVar value = other.try_get(item.first);
+            PyVar value = other.try_get(vm, item.first);
             if(value == nullptr) return vm->False;
             if(!vm->py_eq(item.second, value)) return vm->False;
         }
diff --git a/src/vm.cpp b/src/vm.cpp
index d8f51a26..2ad6034d 100644
--- a/src/vm.cpp
+++ b/src/vm.cpp
@@ -566,14 +566,14 @@ PyVar VM::__py_exec_internal(const CodeObject_& code, PyVar globals, PyVar local
     if(globals_dict){
         globals_dict->clear();
         globals_obj->attr().apply([&](StrName k, PyVar v){
-            globals_dict->set(VAR(k.sv()), v);
+            globals_dict->set(vm, VAR(k.sv()), v);
         });
     }
 
     if(locals_dict){
         locals_dict->clear();
         locals_closure->apply([&](StrName k, PyVar v){
-            locals_dict->set(VAR(k.sv()), v);
+            locals_dict->set(vm, VAR(k.sv()), v);
         });
     }
     return retval;
@@ -921,11 +921,11 @@ void VM::__unpack_as_dict(ArgsView args, Dict& dict){
             // maybe this check should be done in the compile time
             if(w.level != 2) TypeError("expected level 2 star wrapper");
             const Dict& other = CAST(Dict&, w.obj);
-            dict.update(other);
+            dict.update(this, other);
         }else{
             const Tuple& t = CAST(Tuple&, obj);
             if(t.size() != 2) TypeError("expected tuple of length 2");
-            dict.set(t[0], t[1]);
+            dict.set(this, t[0], t[1]);
         }
     }
 }
@@ -966,7 +966,7 @@ void VM::__prepare_py_call(PyVar* buffer, ArgsView args, ArgsView kwargs, const
     
     PyVar vkwargs;
     if(decl->starred_kwarg != -1){
-        vkwargs = VAR(Dict(this));
+        vkwargs = VAR(Dict());
         buffer[decl->starred_kwarg] = vkwargs;
     }else{
         vkwargs = nullptr;
@@ -984,7 +984,7 @@ void VM::__prepare_py_call(PyVar* buffer, ArgsView args, ArgsView kwargs, const
                 TypeError(_S(key.escape(), " is an invalid keyword argument for ", co->name, "()"));
             }else{
                 Dict& dict = _CAST(Dict&, vkwargs);
-                dict.set(VAR(key.sv()), kwargs[j+1]);
+                dict.set(this, VAR(key.sv()), kwargs[j+1]);
             }
         }
     }
@@ -1559,7 +1559,7 @@ void VM::bind__len__(Type type, i64 (*f)(VM*, PyVar)){
 #undef BIND_BINARY_SPECIAL
 
 
-void Dict::_probe_0(PyVar key, bool &ok, int &i) const{
+void Dict::_probe_0(VM* vm, PyVar key, bool &ok, int &i) const{
     ok = false;
     i64 hash = vm->py_hash(key);
     i = hash & _mask;
@@ -1574,7 +1574,7 @@ void Dict::_probe_0(PyVar key, bool &ok, int &i) const{
     }
 }
 
-void Dict::_probe_1(PyVar key, bool &ok, int &i) const{
+void Dict::_probe_1(VM* vm, PyVar key, bool &ok, int &i) const{
     ok = false;
     i = vm->py_hash(key) & _mask;
     while(_items[i].first != nullptr) {