diff --git a/mime/mime.go b/mime/mime.go
index b3a1408..7a5fd4d 100644
--- a/mime/mime.go
+++ b/mime/mime.go
@@ -5,6 +5,7 @@ var Types = map[string]string{
 	"flac": "audio/x-flac",
 	"aac":  "audio/x-aac",
 	"m4a":  "audio/m4a",
+	"m4b":  "audio/m4b",
 	"ogg":  "audio/ogg",
 	"opus": "audio/ogg",
 }