diff --git a/hm_pyhelper/tests/test_hardware_definitions.py b/hm_pyhelper/tests/test_hardware_definitions.py
index 2cc40b6..28ac383 100644
--- a/hm_pyhelper/tests/test_hardware_definitions.py
+++ b/hm_pyhelper/tests/test_hardware_definitions.py
@@ -196,5 +196,6 @@ def test_is_linxdot_rk3566(self):
                 self.assertTrue(is_linxdot_rk3566())
             # in absence of the env, it should look for /proc/device-tree/model
             # which will not exist on test environment.
-            with self.assertRaises(FileNotFoundError):
+            with patch.dict(os.environ, {'BALENA_DEVICE_TYPE': "something"}):
+                self.assertRaises(FileNotFoundError)
                 self.assertFalse(is_linxdot_rk3566())