diff --git a/gc.c b/gc.c
index 3c9adf3b007384..b4842ba76705db 100644
--- a/gc.c
+++ b/gc.c
@@ -6842,37 +6842,33 @@ gc_aging(rb_objspace_t *objspace, VALUE obj)
     objspace->marked_slots++;
 }
 
-NOINLINE(static void gc_mark_ptr(rb_objspace_t *objspace, VALUE obj));
+NOINLINE(static void gc_mark_ptr(VALUE obj, void *data));
 static void reachable_objects_from_callback(VALUE obj);
 
 static void
-gc_mark_ptr(rb_objspace_t *objspace, VALUE obj)
+gc_mark_ptr(VALUE obj, void *data)
 {
-    if (LIKELY(during_gc)) {
-        rgengc_check_relation(objspace, obj);
-        if (!gc_mark_set(objspace, obj)) return; /* already marked */
+    rb_objspace_t *objspace = (rb_objspace_t *)data;
+    rgengc_check_relation(objspace, obj);
+    if (!gc_mark_set(objspace, obj)) return; /* already marked */
 
-        if (0) { // for debug GC marking miss
-            if (objspace->rgengc.parent_object) {
-                RUBY_DEBUG_LOG("%p (%s) parent:%p (%s)",
-                               (void *)obj, obj_type_name(obj),
-                               (void *)objspace->rgengc.parent_object, obj_type_name(objspace->rgengc.parent_object));
-            }
-            else {
-                RUBY_DEBUG_LOG("%p (%s)", (void *)obj, obj_type_name(obj));
-            }
+    if (0) { // for debug GC marking miss
+        if (objspace->rgengc.parent_object) {
+            RUBY_DEBUG_LOG("%p (%s) parent:%p (%s)",
+                           (void *)obj, obj_type_name(obj),
+                           (void *)objspace->rgengc.parent_object, obj_type_name(objspace->rgengc.parent_object));
         }
-
-        if (UNLIKELY(RB_TYPE_P(obj, T_NONE))) {
-            rp(obj);
-            rb_bug("try to mark T_NONE object"); /* check here will help debugging */
+        else {
+            RUBY_DEBUG_LOG("%p (%s)", (void *)obj, obj_type_name(obj));
         }
-        gc_aging(objspace, obj);
-        gc_grey(objspace, obj);
     }
-    else {
-        reachable_objects_from_callback(obj);
+
+    if (UNLIKELY(RB_TYPE_P(obj, T_NONE))) {
+        rp(obj);
+        rb_bug("try to mark T_NONE object"); /* check here will help debugging */
     }
+    gc_aging(objspace, obj);
+    gc_grey(objspace, obj);
 }
 
 static inline void
@@ -6891,14 +6887,14 @@ gc_mark_and_pin(rb_objspace_t *objspace, VALUE obj)
 {
     if (!is_markable_object(obj)) return;
     gc_pin(objspace, obj);
-    gc_mark_ptr(objspace, obj);
+    reachable_objects_from_callback(obj);
 }
 
 static inline void
 gc_mark(rb_objspace_t *objspace, VALUE obj)
 {
     if (!is_markable_object(obj)) return;
-    gc_mark_ptr(objspace, obj);
+    reachable_objects_from_callback(obj);
 }
 
 void
@@ -6926,7 +6922,7 @@ rb_gc_mark_and_move(VALUE *ptr)
         *ptr = rb_gc_location(*ptr);
     }
     else {
-        gc_mark_ptr(objspace, *ptr);
+        reachable_objects_from_callback(*ptr);
     }
 }
 
@@ -8536,7 +8532,6 @@ gc_marks(rb_objspace_t *objspace, int full_mark)
     bool marking_finished = false;
 
     /* setup marking */
-
     gc_marks_start(objspace, full_mark);
     if (!is_incremental_marking(objspace)) {
         gc_marks_rest(objspace);
@@ -9210,6 +9205,10 @@ gc_start(rb_objspace_t *objspace, unsigned int reason)
     /* reason may be clobbered, later, so keep set immediate_sweep here */
     objspace->flags.immediate_sweep = !!(reason & GPR_FLAG_IMMEDIATE_SWEEP);
 
+    rb_ractor_t *cr = GET_RACTOR();
+    struct gc_mark_func_data_struct prev_mfd = cr->mfd;
+    rb_ractor_init_mfd(cr);
+
     /* Explicitly enable compaction (GC.compact) */
     if (do_full_mark && ruby_enable_autocompact) {
         objspace->flags.during_compacting = TRUE;
@@ -9316,6 +9315,8 @@ gc_start(rb_objspace_t *objspace, unsigned int reason)
 
     gc_exit(objspace, gc_enter_event_start, &lock_lev);
     return TRUE;
+
+    cr->mfd = prev_mfd;
 }
 
 static void
@@ -11671,7 +11672,7 @@ static void
 reachable_objects_from_callback(VALUE obj)
 {
     rb_ractor_t *cr = GET_RACTOR();
-    cr->mfd->mark_func(obj, cr->mfd->data);
+    cr->mfd.mark_func(obj, cr->mfd.data);
 }
 
 void
@@ -11688,9 +11689,9 @@ rb_objspace_reachable_objects_from(VALUE obj, void (func)(VALUE, void *), void *
             struct gc_mark_func_data_struct mfd = {
                 .mark_func = func,
                 .data = data,
-            }, *prev_mfd = cr->mfd;
+            }, prev_mfd = cr->mfd;
 
-            cr->mfd = &mfd;
+            cr->mfd = mfd;
             gc_mark_children(objspace, obj);
             cr->mfd = prev_mfd;
         }
@@ -11731,9 +11732,9 @@ objspace_reachable_objects_from_root(rb_objspace_t *objspace, void (func)(const
     struct gc_mark_func_data_struct mfd = {
         .mark_func = root_objects_from,
         .data = &data,
-    }, *prev_mfd = cr->mfd;
+    }, prev_mfd = cr->mfd;
 
-    cr->mfd = &mfd;
+    cr->mfd = mfd;
     gc_mark_roots(objspace, &data.category);
     cr->mfd = prev_mfd;
 }
@@ -13770,6 +13771,13 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self)
     return Qnil;
 }
 
+void
+rb_ractor_init_mfd(rb_ractor_t *r)
+{
+    r->mfd.mark_func = gc_mark_ptr;
+    r->mfd.data = (void *)&rb_objspace;
+}
+
 /*
  * Document-module: ObjectSpace
  *
diff --git a/internal/gc.h b/internal/gc.h
index 29344224744e1d..44808645d00774 100644
--- a/internal/gc.h
+++ b/internal/gc.h
@@ -125,6 +125,13 @@ const char *rb_raw_obj_info(char *const buff, const size_t buff_size, VALUE obj)
 
 size_t rb_size_pool_slot_size(unsigned char pool_id);
 
+typedef void (*rb_ractor_value_visitor_func)(VALUE v, void *data);
+
+struct gc_mark_func_data_struct {
+    void *data;
+    rb_ractor_value_visitor_func mark_func;
+};
+
 struct rb_execution_context_struct; /* in vm_core.h */
 struct rb_objspace; /* in vm_core.h */
 
@@ -234,6 +241,7 @@ VALUE rb_gc_id2ref_obj_tbl(VALUE objid);
 VALUE rb_define_finalizer_no_check(VALUE obj, VALUE block);
 
 void rb_gc_mark_and_move(VALUE *ptr);
+void rb_ractor_init_mfd(rb_ractor_t *r);
 
 #define rb_gc_mark_and_move_ptr(ptr) do { \
     VALUE _obj = (VALUE)*(ptr); \
diff --git a/ractor.c b/ractor.c
index e0919ac56b1804..165200c5879d51 100644
--- a/ractor.c
+++ b/ractor.c
@@ -1903,6 +1903,7 @@ ractor_alloc(VALUE klass)
     VALUE rv = TypedData_Make_Struct(klass, rb_ractor_t, &ractor_data_type, r);
     FL_SET_RAW(rv, RUBY_FL_SHAREABLE);
     r->pub.self = rv;
+    rb_ractor_init_mfd(r);
     VM_ASSERT(ractor_status_p(r, ractor_created));
     return rv;
 }
@@ -1921,7 +1922,7 @@ rb_ractor_main_alloc(void)
     r->name = Qnil;
     r->pub.self = Qnil;
     ruby_single_main_ractor = r;
-
+    rb_ractor_init_mfd(r);
     return r;
 }
 
diff --git a/ractor_core.h b/ractor_core.h
index 38aded15074bef..4645c058c3e110 100644
--- a/ractor_core.h
+++ b/ractor_core.h
@@ -186,10 +186,7 @@ struct rb_ractor_struct {
     rb_ractor_newobj_cache_t newobj_cache;
 
     // gc.c rb_objspace_reachable_objects_from
-    struct gc_mark_func_data_struct {
-        void *data;
-        void (*mark_func)(VALUE v, void *data);
-    } *mfd;
+    struct gc_mark_func_data_struct mfd;
 }; // rb_ractor_t is defined in vm_core.h