diff --git a/eval.c b/eval.c
index 0a8d32eb2f..7118c1556f 100644
--- a/eval.c
+++ b/eval.c
@@ -1273,6 +1273,18 @@ hidden_identity_hash_new(void)
     return hash;
 }
 
+static VALUE
+refinement_superclass(VALUE superclass)
+{
+    if (RB_TYPE_P(superclass, T_MODULE)) {
+	/* FIXME: Should ancestors of superclass be used here? */
+	return rb_include_class_new(superclass, rb_cBasicObject);
+    }
+    else {
+	return superclass;
+    }
+}
+
 /*!
  * \private
  * \todo can be static?
@@ -1304,10 +1316,7 @@ rb_using_refinement(rb_cref_t *cref, VALUE klass, VALUE module)
 	}
     }
     FL_SET(module, RMODULE_IS_OVERLAID);
-    if (RB_TYPE_P(superclass, T_MODULE)) {
-	superclass = rb_include_class_new(superclass,
-					  RCLASS_SUPER(superclass));
-    }
+    superclass = refinement_superclass(superclass);
     c = iclass = rb_include_class_new(module, superclass);
     RCLASS_REFINED_CLASS(c) = klass;
 
@@ -1402,10 +1411,7 @@ add_activated_refinement(VALUE activated_refinements,
 	}
     }
     FL_SET(refinement, RMODULE_IS_OVERLAID);
-    if (RB_TYPE_P(superclass, T_MODULE)) {
-	superclass = rb_include_class_new(superclass,
-					  RCLASS_SUPER(superclass));
-    }
+    superclass = refinement_superclass(superclass);
     c = iclass = rb_include_class_new(refinement, superclass);
     RCLASS_REFINED_CLASS(c) = klass;
     refinement = RCLASS_SUPER(refinement);
@@ -1460,13 +1466,9 @@ rb_mod_refine(VALUE module, VALUE klass)
     }
     refinement = rb_hash_lookup(refinements, klass);
     if (NIL_P(refinement)) {
+	VALUE superclass = refinement_superclass(klass);
 	refinement = rb_module_new();
-	if (RB_TYPE_P(klass, T_MODULE)) {
-	    rb_include_module(refinement, klass);
-	}
-	else {
-	    RCLASS_SET_SUPER(refinement, klass);
-	}
+	RCLASS_SET_SUPER(refinement, superclass);
 	FL_SET(refinement, RMODULE_IS_REFINEMENT);
 	CONST_ID(id_refined_class, "__refined_class__");
 	rb_ivar_set(refinement, id_refined_class, klass);