diff --git a/data/event-schemas/schema/m.room.message$m.audio.yaml b/data/event-schemas/schema/m.room.message$m.audio.yaml
index a1116c59..d138de38 100644
--- a/data/event-schemas/schema/m.room.message$m.audio.yaml
+++ b/data/event-schemas/schema/m.room.message$m.audio.yaml
@@ -54,6 +54,8 @@ properties:
           Required if the file is unencrypted. The URL (typically [`mxc://` URI](/client-server-api/#matrix-content-mxc-uris))
           to the audio clip.
         type: string
+        format: mx-mxc-uri
+        pattern: "^mxc:\\/\\/"
       file:
         description: |-
           Required if the file is encrypted. Information on the encrypted