diff --git a/include/pocketpy/interpreter/vm.h b/include/pocketpy/interpreter/vm.h
index c97a5aa8..62ac4f40 100644
--- a/include/pocketpy/interpreter/vm.h
+++ b/include/pocketpy/interpreter/vm.h
@@ -55,7 +55,7 @@ void VM__pop_frame(VM* self);
 bool pk__parse_int_slice(py_Ref slice, int length, int* start, int* stop, int* step);
 bool pk__normalize_index(int* index, int length);
 
-void pk__mark_value(py_TValue*);
+#define pk__mark_value(val) if((val)->is_ptr && !(val)->_obj->gc_marked) PyObject__mark((val)->_obj)
 void pk__mark_namedict(NameDict*);
 void pk__tp_set_marker(py_Type type, void (*gc_mark)(void*));
 bool pk__object_new(int argc, py_Ref argv);
diff --git a/include/pocketpy/objects/namedict.h b/include/pocketpy/objects/namedict.h
index 4d304b5e..50dd0572 100644
--- a/include/pocketpy/objects/namedict.h
+++ b/include/pocketpy/objects/namedict.h
@@ -25,4 +25,4 @@ void ModuleDict__dtor(ModuleDict* self);
 void ModuleDict__set(ModuleDict* self, const char* key, py_TValue val);
 py_TValue* ModuleDict__try_get(ModuleDict* self, const char* path);
 bool ModuleDict__contains(ModuleDict* self, const char* path);
-void ModuleDict__apply_mark(ModuleDict* self, void (*marker)(py_TValue*));
+void ModuleDict__apply_mark(ModuleDict* self);
diff --git a/include/pocketpy/objects/object.h b/include/pocketpy/objects/object.h
index 822df540..1f63be0f 100644
--- a/include/pocketpy/objects/object.h
+++ b/include/pocketpy/objects/object.h
@@ -24,3 +24,4 @@ void* PyObject__userdata(PyObject* self);
 #define PK_OBJ_SLOTS_SIZE(slots) ((slots) >= 0 ? sizeof(py_TValue) * (slots) : sizeof(NameDict))
 
 void PyObject__dtor(PyObject* self);
+void PyObject__mark(PyObject* self);
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index ea5f1b5f..2876d815 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -585,14 +585,6 @@ void PyObject__dtor(PyObject* self) {
     if(self->slots == -1) NameDict__dtor(PyObject__dict(self));
 }
 
-static void mark_object(PyObject* obj);
-
-void pk__mark_value(py_TValue* val) {
-    if(val->is_ptr && !val->_obj->gc_marked) {
-        mark_object(val->_obj);
-    }
-}
-
 void pk__mark_namedict(NameDict* dict) {
     for(int i = 0; i < dict->length; i++) {
         NameDict_KV* kv = c11__at(NameDict_KV, dict, i);
@@ -606,9 +598,9 @@ void pk__tp_set_marker(py_Type type, void (*gc_mark)(void*)) {
     ti->gc_mark = gc_mark;
 }
 
-static void mark_object(PyObject* obj) {
+void PyObject__mark(PyObject* obj) {
     assert(!obj->gc_marked);
-    
+
     obj->gc_marked = true;
 
     if(obj->slots > 0) {
@@ -654,7 +646,7 @@ void ManagedHeap__mark(ManagedHeap* self) {
         pk__mark_value(&vm->ascii_literals[i]);
     }
     // mark modules
-    ModuleDict__apply_mark(&vm->modules, pk__mark_value);
+    ModuleDict__apply_mark(&vm->modules);
     // mark types
     int types_length = vm->types.length;
     // 0-th type is placeholder
diff --git a/src/objects/namedict.c b/src/objects/namedict.c
index 498fdacb..beb262e4 100644
--- a/src/objects/namedict.c
+++ b/src/objects/namedict.c
@@ -1,4 +1,5 @@
 #include "pocketpy/objects/namedict.h"
+#include "pocketpy/objects/object.h"
 
 #define SMALLMAP_T__SOURCE
 #define K uint16_t
@@ -74,8 +75,8 @@ bool ModuleDict__contains(ModuleDict* self, const char* path) {
     return ModuleDict__try_get(self, path) != NULL;
 }
 
-void ModuleDict__apply_mark(ModuleDict *self, void (*marker)(py_TValue*)) {
-    if(self->left) ModuleDict__apply_mark(self->left, marker);
-    if(self->right) ModuleDict__apply_mark(self->right, marker);
-    marker(&self->module);
+void ModuleDict__apply_mark(ModuleDict *self) {
+    PyObject__mark(self->module._obj);
+    if(self->left) ModuleDict__apply_mark(self->left);
+    if(self->right) ModuleDict__apply_mark(self->right);
 }