diff --git a/ChangeLog b/ChangeLog
index 9c5862dbe1..7bdeddec37 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Sep 15 11:39:43 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.c (mark_entry, mark_key, mark_keyvalue): adjust callback
+	  argument types.
+
 Thu Sep 15 01:44:10 2011  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* ext/tk/*: Change encoding from EUC-JP to UTF-8
diff --git a/gc.c b/gc.c
index 48a1db32d5..f25f9cd48d 100644
--- a/gc.c
+++ b/gc.c
@@ -1444,10 +1444,10 @@ struct mark_tbl_arg {
 };
 
 static int
-mark_entry(ID key, VALUE value, st_data_t data)
+mark_entry(st_data_t key, st_data_t value, st_data_t data)
 {
     struct mark_tbl_arg *arg = (void*)data;
-    gc_mark(arg->objspace, value, arg->lev);
+    gc_mark(arg->objspace, (VALUE)value, arg->lev);
     return ST_CONTINUE;
 }
 
@@ -1462,10 +1462,10 @@ mark_tbl(rb_objspace_t *objspace, st_table *tbl, int lev)
 }
 
 static int
-mark_key(VALUE key, VALUE value, st_data_t data)
+mark_key(st_data_t key, st_data_t value, st_data_t data)
 {
     struct mark_tbl_arg *arg = (void*)data;
-    gc_mark(arg->objspace, key, arg->lev);
+    gc_mark(arg->objspace, (VALUE)key, arg->lev);
     return ST_CONTINUE;
 }
 
@@ -1486,11 +1486,11 @@ rb_mark_set(st_table *tbl)
 }
 
 static int
-mark_keyvalue(VALUE key, VALUE value, st_data_t data)
+mark_keyvalue(st_data_t key, st_data_t value, st_data_t data)
 {
     struct mark_tbl_arg *arg = (void*)data;
-    gc_mark(arg->objspace, key, arg->lev);
-    gc_mark(arg->objspace, value, arg->lev);
+    gc_mark(arg->objspace, (VALUE)key, arg->lev);
+    gc_mark(arg->objspace, (VALUE)value, arg->lev);
     return ST_CONTINUE;
 }