diff --git a/ChangeLog b/ChangeLog
index c214f213ef..c3d1c061a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Aug  9 10:53:57 2013  Kazuki Tsujimoto  <kazuki@callcc.net>
+
+	* time.c (get_timeval, get_new_timeval): use rb_obj_class()
+	  instead of CLASS_OF() because CLASS_OF() may return
+	  a singleton class.
+
 Fri Aug  9 10:42:11 2013  Kazuki Tsujimoto  <kazuki@callcc.net>
 
 	* vm_insnhelper.c (vm_invoke_block): returning from lambda proc
diff --git a/time.c b/time.c
index 20476e9343..68a6b7e95e 100644
--- a/time.c
+++ b/time.c
@@ -1817,7 +1817,7 @@ get_timeval(VALUE obj)
     struct time_object *tobj;
     TypedData_Get_Struct(obj, struct time_object, &time_data_type, tobj);
     if (!TIME_INIT_P(tobj)) {
-	rb_raise(rb_eTypeError, "uninitialized %"PRIsVALUE, CLASS_OF(obj));
+	rb_raise(rb_eTypeError, "uninitialized %"PRIsVALUE, rb_obj_class(obj));
     }
     return tobj;
 }
@@ -1828,7 +1828,7 @@ get_new_timeval(VALUE obj)
     struct time_object *tobj;
     TypedData_Get_Struct(obj, struct time_object, &time_data_type, tobj);
     if (TIME_INIT_P(tobj)) {
-	rb_raise(rb_eTypeError, "already initialized %"PRIsVALUE, CLASS_OF(obj));
+	rb_raise(rb_eTypeError, "already initialized %"PRIsVALUE, rb_obj_class(obj));
     }
     return tobj;
 }