diff --git a/supersensor.yaml b/supersensor.yaml
index 31cccfd..1d3ddbb 100644
--- a/supersensor.yaml
+++ b/supersensor.yaml
@@ -514,7 +514,7 @@ sensor:
     name: "BME680 AQ"
     id: bme680_aq
     icon: "mdi:gauge"
-    unit_of_measurement: %
+    unit_of_measurement: "%"
     # Calculation from https://github.com/thstielow/raspi-bme680-iaq
     lambda: |-
       float ph_slope = 0.03;