diff --git a/pi_mqtt_gpio/__init__.py b/pi_mqtt_gpio/__init__.py
index 2c37d8b0ce4046fd86d478428811ce1f84d066dc..f23934d2c4737ce321665361c73c9bd118d86997 100644
--- a/pi_mqtt_gpio/__init__.py
+++ b/pi_mqtt_gpio/__init__.py
@@ -310,6 +310,9 @@ sensor_inputs:
         required: no
         default: 2
         min: 0
+      unit_of_measurement:
+        type: string
+        required: no
 
 stream_reads:
   type: list