diff --git a/test/attributes/attributeforinstanceof.js b/test/attributes/attributeforinstanceof.js
index a50d8ca5..21962a65 100644
--- a/test/attributes/attributeforinstanceof.js
+++ b/test/attributes/attributeforinstanceof.js
@@ -66,6 +66,21 @@ describe("attributes/attributeforinstanceof", function () {
             assert(exceptionCaught instanceof gpf.Error.ClassAttributeOnly);
         });
 
+        it("can't be used twice", function () {
+            var exceptionCaught;
+            try {
+                gpf.define({
+                    $class: "Attribute",
+                    $extend: gpf.attributes.Attribute,
+                    $attributes: [onInstanceOfA, onInstanceOfA],
+                    test: function () {}
+                });
+            } catch (e) {
+                exceptionCaught = e;
+            }
+            assert(exceptionCaught instanceof gpf.Error.UniqueAttributeUsedTwice);
+        });
+
         describe("When used properly", function () {
 
             var AttributeForA,