diff --git a/test/types.js b/test/types.js
index 358f7dd..03634e6 100644
--- a/test/types.js
+++ b/test/types.js
@@ -7,13 +7,13 @@ var typeforce = require('typeforce')
 describe('types', function () {
   describe('BigInt/ECPoint', function () {
     it('return true for duck types', function () {
-      assert(types.BigInt(new function BigInteger () {}))
-      assert(types.ECPoint(new function Point () {}))
+      assert(types.BigInt(new function BigInteger () {}()))
+      assert(types.ECPoint(new function Point () {}()))
     })
 
     it('return false for bad types', function () {
-      assert(!types.BigInt(new function NotABigInteger () {}))
-      assert(!types.ECPoint(new function NotAPoint () {}))
+      assert(!types.BigInt(new function NotABigInteger () {}()))
+      assert(!types.ECPoint(new function NotAPoint () {}()))
     })
   })