diff --git a/api/client-server/joining.yaml b/api/client-server/joining.yaml
index 1bd7224f..1dcf769f 100644
--- a/api/client-server/joining.yaml
+++ b/api/client-server/joining.yaml
@@ -104,7 +104,7 @@ paths:
             properties:
               room_id:
                 type: string
-                description: The joined room id
+                description: The joined room ID.
             required: ["room_id"]
         403:
           description: |-
@@ -216,7 +216,7 @@ paths:
             properties:
               room_id:
                 type: string
-                description: The joined room id
+                description: The joined room ID.
             required: ["room_id"]
         403:
           description: |-