diff --git a/devices/__init__.py b/devices/__init__.py
index 40ba95f..faafc17 100644
--- a/devices/__init__.py
+++ b/devices/__init__.py
@@ -475,6 +475,8 @@ class tradfri_button(base):
     KEY_ACTION = "action"
     KEY_ACTION_DURATION = "action_duration"
     #
+    TX_TOPIC = ''
+    #
     RX_KEYS = [KEY_LINKQUALITY, KEY_BATTERY, KEY_ACTION]
     RX_IGNORE_KEYS = ['update', KEY_ACTION_DURATION]