diff --git a/ChangeLog b/ChangeLog
index df3cec8270..dbd9135bbe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jun 18 10:17:37 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* variable.c (rb_autoload): fix WB miss.
+
 Tue Jun 18 04:20:18 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (gc_mark_children): don't need to care about T_ZOMBIE here.
diff --git a/variable.c b/variable.c
index 749d928b17..79fcca0280 100644
--- a/variable.c
+++ b/variable.c
@@ -1621,6 +1621,7 @@ rb_autoload(VALUE mod, ID id, const char *file)
 	if (!tbl) tbl = RCLASS_IV_TBL(mod) = st_init_numtable();
 	av = (st_data_t)TypedData_Wrap_Struct(0, &autoload_data_type, 0);
 	st_add_direct(tbl, (st_data_t)autoload, av);
+	OBJ_WRITTEN(mod, Qnil, av);
 	DATA_PTR(av) = tbl = st_init_numtable();
     }
     fn = rb_str_new2(file);