diff --git a/artiq/test/lit/integration/str.py b/artiq/test/lit/integration/str.py
index 45b430d2a..9d75399e9 100644
--- a/artiq/test/lit/integration/str.py
+++ b/artiq/test/lit/integration/str.py
@@ -2,4 +2,9 @@
 # RUN: %python %s
 
 assert "xy" == "xy"
+assert not ("xy" == "xz")
+
+assert "xy" != "xz"
+assert not ("xy" != "xy")
+
 assert ("x" + "y") == "xy"