1 files changed, 1 insertions, 1 deletions
diff --git a/class.c b/class.c
index 599cbd689e..6674ae1a9d 100644
--- a/class.c
+++ b/class.c
@@ -180,7 +180,7 @@ rb_mod_init_copy(VALUE clone, VALUE orig)
 VALUE
 rb_class_init_copy(VALUE clone, VALUE orig)
 {
-    if (RCLASS_SUPER(clone) != 0) {
+    if (RCLASS_SUPER(clone) != 0 || clone == rb_cBasicObject) {
 	rb_raise(rb_eTypeError, "already initialized class");
     }
     if (FL_TEST(orig, FL_SINGLETON)) {