diff --git a/tests/test_calculator.py b/tests/test_calculator.py
index c61f070..365cbc7 100644
--- a/tests/test_calculator.py
+++ b/tests/test_calculator.py
@@ -5,6 +5,7 @@
 def test_add():
     assert add(2, 3) == 5
     assert add(-1, 1) == 0
+    assert add(2, 2) == 4
 
 
 def test_multiply():