diff --git a/test/test_vector.py b/test/test_vector.py
index 04d7304..d3b0f65 100644
--- a/test/test_vector.py
+++ b/test/test_vector.py
@@ -11,6 +11,11 @@ class TestVector(unittest.TestCase):
         self.assertIsInstance(v3, Vector)
         self.assertEqual(v3.x, v1.x + v2.x)
         
+    def test_dot_failure(self):
+        with self.assertRaises(ValueError):
+            v1 = Vector(1, 2, 3)
+            v1.dot(3)
+
     def test_dot_product(self):
         v1 = Vector(1, 2, 3)
         v2 = Vector(-3, -2, -1)