diff --git a/include/mruby/internal.h b/include/mruby/internal.h
index a2948961a..05d7b9a26 100644
--- a/include/mruby/internal.h
+++ b/include/mruby/internal.h
@@ -186,8 +186,7 @@ mrb_bool mrb_ident_p(const char *s, mrb_int len);
 /* GC functions */
 void mrb_gc_mark_gv(mrb_state*);
 void mrb_gc_free_gv(mrb_state*);
-void mrb_gc_mark_iv(mrb_state*, struct RObject*);
-size_t mrb_gc_mark_iv_size(mrb_state*, struct RObject*);
+size_t mrb_gc_mark_iv(mrb_state*, struct RObject*);
 void mrb_gc_free_iv(mrb_state*, struct RObject*);
 
 /* VM */
diff --git a/src/gc.c b/src/gc.c
index 5434bd0d0..839213e70 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -610,8 +610,7 @@ gc_mark_children(mrb_state *mrb, mrb_gc *gc, struct RBasic *obj)
 
   case MRB_TT_OBJECT:
   case MRB_TT_CDATA:
-    mrb_gc_mark_iv(mrb, (struct RObject*)obj);
-    children += mrb_gc_mark_iv_size(mrb, (struct RObject*)obj);
+    children += mrb_gc_mark_iv(mrb, (struct RObject*)obj);
     break;
 
   case MRB_TT_PROC:
@@ -675,9 +674,8 @@ gc_mark_children(mrb_state *mrb, mrb_gc *gc, struct RBasic *obj)
     break;
 
   case MRB_TT_HASH:
-    mrb_gc_mark_iv(mrb, (struct RObject*)obj);
+    children += mrb_gc_mark_iv(mrb, (struct RObject*)obj);
     mrb_gc_mark_hash(mrb, (struct RHash*)obj);
-    children += mrb_gc_mark_iv_size(mrb, (struct RObject*)obj);
     children += mrb_gc_mark_hash_size(mrb, (struct RHash*)obj);
     break;
 
@@ -702,7 +700,7 @@ gc_mark_children(mrb_state *mrb, mrb_gc *gc, struct RBasic *obj)
     break;
 
   case MRB_TT_EXCEPTION:
-    mrb_gc_mark_iv(mrb, (struct RObject*)obj);
+    children += mrb_gc_mark_iv(mrb, (struct RObject*)obj);
     if (((struct RException*)obj)->mesg) {
       mrb_gc_mark(mrb, (struct RBasic*)((struct RException*)obj)->mesg);
       children++;
diff --git a/src/variable.c b/src/variable.c
index 4c51a8a61..4a373f33f 100644
--- a/src/variable.c
+++ b/src/variable.c
@@ -255,15 +255,10 @@ mrb_gc_free_gv(mrb_state *mrb)
     iv_free(mrb, mrb->globals);
 }
 
-void
+size_t
 mrb_gc_mark_iv(mrb_state *mrb, struct RObject *obj)
 {
   mark_tbl(mrb, obj->iv);
-}
-
-size_t
-mrb_gc_mark_iv_size(mrb_state *mrb, struct RObject *obj)
-{
   return iv_size(mrb, obj->iv);
 }