diff --git a/etiquette/constants.py b/etiquette/constants.py
index 776474f..e6f1536 100644
--- a/etiquette/constants.py
+++ b/etiquette/constants.py
@@ -135,6 +135,7 @@ ADDITIONAL_MIMETYPES = {
     'ac3': 'audio/ac3',
     'dts': 'audio/dts',
     'm4a': 'audio/mp4',
+    'opus': 'audio/ogg',
 
     'mkv': 'video/x-matroska',