diff --git a/examples/demo.py b/examples/demo.py
index 62c0f7ee5fe975f0d4097be41396b558e82eec50..59f7b3d45399777c36c49b0b1690953dbe3387cc 100644
--- a/examples/demo.py
+++ b/examples/demo.py
@@ -33,3 +33,4 @@ cl.enqueue_copy(queue, res_np, res_g)
 # Check on CPU with Numpy:
 print(res_np - (a_np + b_np))
 print(np.linalg.norm(res_np - (a_np + b_np)))
+assert np.allclose(res_np, a_np + b_np)