diff --git a/source/_integrations/binary_sensor.mqtt.markdown b/source/_integrations/binary_sensor.mqtt.markdown
index ec345da14a3..eaf7bffa4ca 100644
--- a/source/_integrations/binary_sensor.mqtt.markdown
+++ b/source/_integrations/binary_sensor.mqtt.markdown
@@ -129,7 +129,7 @@ encoding:
   type: string
   default: "utf-8"
 entity_category:
-  description: The [category](https://developers.home-assistant.io/docs/core/entity/#generic-properties) of the entity.
+  description: The [category](https://developers.home-assistant.io/docs/core/entity/#generic-properties) of the entity. When set, the entity category must be `diagnostic` for sensors.
   required: false
   type: string
   default: None
diff --git a/source/_integrations/sensor.mqtt.markdown b/source/_integrations/sensor.mqtt.markdown
index cc317fe6c5c..bacf9269945 100644
--- a/source/_integrations/sensor.mqtt.markdown
+++ b/source/_integrations/sensor.mqtt.markdown
@@ -122,7 +122,7 @@ encoding:
   type: string
   default: "utf-8"
 entity_category:
-  description: The [category](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity.
+  description: The [category](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity. When set, the entity category must be `diagnostic` for sensors.
   required: false
   type: string
   default: None