diff --git a/iseq.c b/iseq.c
index 631115cce1..c38ac4dd83 100644
--- a/iseq.c
+++ b/iseq.c
@@ -324,6 +324,33 @@ iseq_alloc(void)
     return iseq;
 }
 
+struct count_info {
+    int count;
+};
+
+static void
+count_markables(void *ctx, VALUE obj)
+{
+    struct count_info * my_count = (struct count_info *)ctx;
+    my_count->count += 1;
+}
+
+static VALUE
+iseqw_object_count(VALUE self)
+{
+    rb_iseq_t * iseq = iseqw_check(self);
+    struct count_info my_count = {0,};
+    rb_iseq_each_value(iseq, count_markables, &my_count);
+    return INT2NUM(my_count.count);
+}
+
+static VALUE
+iseqw_size(VALUE self)
+{
+    rb_iseq_t * iseq = iseqw_check(self);
+    return INT2NUM(iseq->body->iseq_size);
+}
+
 VALUE
 rb_iseq_pathobj_new(VALUE path, VALUE realpath)
 {
@@ -3075,6 +3102,8 @@ Init_ISeq(void)
     rb_define_method(rb_cISeq, "first_lineno", iseqw_first_lineno, 0);
     rb_define_method(rb_cISeq, "trace_points", iseqw_trace_points, 0);
     rb_define_method(rb_cISeq, "each_child", iseqw_each_child, 0);
+    rb_define_method(rb_cISeq, "markable_object_count", iseqw_object_count, 0);
+    rb_define_method(rb_cISeq, "size", iseqw_size, 0);
 
 #if 0 /* TBD */
     rb_define_private_method(rb_cISeq, "marshal_dump", iseqw_marshal_dump, 0);