diff --git a/homeassistant/components/apcupsd/const.py b/homeassistant/components/apcupsd/const.py
index 56bf229579dbb459afe50893adb1f81591bce076..974c860afb81ab05ab3f12cc4cd1017e3da26fc8 100644
--- a/homeassistant/components/apcupsd/const.py
+++ b/homeassistant/components/apcupsd/const.py
@@ -6,4 +6,4 @@ DOMAIN: Final = "apcupsd"
 CONNECTION_TIMEOUT: int = 10
 
 # Field name of last self test retrieved from apcupsd.
-LASTSTEST: Final = "laststest"
+LAST_S_TEST: Final = "laststest"
diff --git a/homeassistant/components/apcupsd/sensor.py b/homeassistant/components/apcupsd/sensor.py
index f2b5943bdf094945ffb4c8c9ffe3ae73cb289543..d4bbfb148e59d2e2e3edb4da38415723068c8948 100644
--- a/homeassistant/components/apcupsd/sensor.py
+++ b/homeassistant/components/apcupsd/sensor.py
@@ -25,7 +25,7 @@ from homeassistant.core import HomeAssistant, callback
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
 
-from .const import DOMAIN, LASTSTEST
+from .const import DOMAIN, LAST_S_TEST
 from .coordinator import APCUPSdCoordinator
 
 PARALLEL_UPDATES = 0
@@ -156,8 +156,8 @@ SENSORS: dict[str, SensorEntityDescription] = {
         device_class=SensorDeviceClass.TEMPERATURE,
         state_class=SensorStateClass.MEASUREMENT,
     ),
-    LASTSTEST: SensorEntityDescription(
-        key=LASTSTEST,
+    LAST_S_TEST: SensorEntityDescription(
+        key=LAST_S_TEST,
         translation_key="last_self_test",
     ),
     "lastxfer": SensorEntityDescription(
@@ -422,7 +422,7 @@ async def async_setup_entry(
     # periodical (or manual) self test since last daemon restart. It might not be available
     # when we set up the integration, and we do not know if it would ever be available. Here we
     # add it anyway and mark it as unknown initially.
-    for resource in available_resources | {LASTSTEST}:
+    for resource in available_resources | {LAST_S_TEST}:
         if resource not in SENSORS:
             _LOGGER.warning("Invalid resource from APCUPSd: %s", resource.upper())
             continue