diff --git a/custom_components/parcelapp/__init__.py b/custom_components/parcelapp/__init__.py
index d8d7f39..7a8f852 100644
--- a/custom_components/parcelapp/__init__.py
+++ b/custom_components/parcelapp/__init__.py
@@ -81,19 +81,27 @@ async def cleanup_old_device(hass: HomeAssistant) -> None:
 
     Older versions of this integration registered a device using a malformed
     identifier -- a bare ``(DOMAIN,)`` tuple instead of the expected
-    ``(DOMAIN, <unique_id>)``. ``device_registry.async_get_device`` is
-    deprecated (scheduled for removal in HA Core 2027.8.0) because device
-    identifiers are no longer guaranteed unique across config entries, and it
-    cannot be used to look up the malformed single-element identifier anyway.
-
-    Iterate the device registry and remove any device that still carries the
-    improper identifier.
+    ``(DOMAIN, <unique_id>)``. That device cannot be looked up with
+    ``device_registry.async_get_device`` (deprecated, and it requires a
+    well-formed identifier pair), and using ``device_registry.devices`` as a
+    mapping is deprecated too (stops working in HA Core 2027.9.0).
+
+    Walk this integration's own config entries with the supported
+    ``async_entries_for_config_entry`` helper and remove any device that still
+    carries the improper identifier.
     """
     device_reg = dr.async_get(hass)
-    for device in list(device_reg.devices.values()):
-        if any(
-            len(identifier) == 1 and identifier[0] == DOMAIN
-            for identifier in device.identifiers
+    removed: set[str] = set()
+    for config_entry in hass.config_entries.async_entries(DOMAIN):
+        for device in dr.async_entries_for_config_entry(
+            device_reg, config_entry.entry_id
         ):
-            _LOGGER.debug("Removing improper device %s", device.name)
-            device_reg.async_remove_device(device.id)
+            if device.id in removed:
+                continue
+            if any(
+                len(identifier) == 1 and identifier[0] == DOMAIN
+                for identifier in device.identifiers
+            ):
+                _LOGGER.debug("Removing improper device %s", device.name)
+                device_reg.async_remove_device(device.id)
+                removed.add(device.id)
diff --git a/custom_components/parcelapp/manifest.json b/custom_components/parcelapp/manifest.json
index b9e21f9..74c619d 100644
--- a/custom_components/parcelapp/manifest.json
+++ b/custom_components/parcelapp/manifest.json
@@ -11,5 +11,5 @@
         "requests>=2.32.3",
         "python-dateutil>=2.9.0"
     ],
-    "version": "1.8.2"
+    "version": "1.8.3"
 }
diff --git a/tests/test_init.py b/tests/test_init.py
new file mode 100644
index 0000000..74acc48
--- /dev/null
+++ b/tests/test_init.py
@@ -0,0 +1,32 @@
+"""Tests for the integration setup helpers."""
+
+import pytest
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import device_registry as dr
+from pytest_homeassistant_custom_component.common import MockConfigEntry
+
+from custom_components.parcelapp import cleanup_old_device
+from custom_components.parcelapp.const import DOMAIN
+
+
+@pytest.mark.asyncio
+async def test_cleanup_removes_only_the_malformed_device(hass: HomeAssistant) -> None:
+    """The legacy bare (DOMAIN,) device is removed, a well-formed one is kept."""
+    entry = MockConfigEntry(
+        domain=DOMAIN, entry_id="entry_1", data={"api_key": "test_api_key"}
+    )
+    entry.add_to_hass(hass)
+    device_reg = dr.async_get(hass)
+    legacy = device_reg.async_get_or_create(
+        config_entry_id=entry.entry_id, identifiers={(DOMAIN,)}, name="Legacy"
+    )
+    current = device_reg.async_get_or_create(
+        config_entry_id=entry.entry_id,
+        identifiers={(DOMAIN, entry.entry_id)},
+        name="Parcel",
+    )
+
+    await cleanup_old_device(hass)
+
+    assert device_reg.async_get(legacy.id) is None
+    assert device_reg.async_get(current.id) is not None