1 files changed, 3 insertions, 0 deletions
diff --git a/class.c b/class.c
index fc99ce4513..d73724bd60 100644
--- a/class.c
+++ b/class.c
@@ -854,6 +854,9 @@ ensure_includable(VALUE klass, VALUE module)
 {
     rb_frozen_class_p(klass);
     Check_Type(module, T_MODULE);
+    if (!NIL_P(rb_refinement_module_get_refined_class(module))) {
+	rb_raise(rb_eArgError, "refinement module is not allowed");
+    }
     OBJ_INFECT(klass, module);
 }