diff --git a/pyproject.toml b/pyproject.toml
index 2d08c48ba0..a3d84a9a3a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -129,7 +129,6 @@ target-version = "py38"
 line-length = 120
 ignore = [
     "E712", # comparison to False
-    "E713", # use `not in`
     "E714", # use `is not`
     "E721", # do not compare types
     "E731", # do not assign a lambda expression
diff --git a/src/tlo/methods/hiv.py b/src/tlo/methods/hiv.py
index cf257cfce9..26e638ec98 100644
--- a/src/tlo/methods/hiv.py
+++ b/src/tlo/methods/hiv.py
@@ -2027,7 +2027,7 @@ def apply(self, person_id):
             return
 
         # Check that they are on Treatment currently:
-        if not (person["hv_art"] in ["on_VL_suppressed", "on_not_VL_suppressed"]):
+        if person["hv_art"] not in ["on_VL_suppressed", "on_not_VL_suppressed"]:
             logger.warning(
                 key="message",
                 data="This event should not be running, Hiv_DecisionToContinueTreatment is for those already on tx")