diff --git a/patoolib/util.py b/patoolib/util.py
index 15ffb57..0d127ff 100644
--- a/patoolib/util.py
+++ b/patoolib/util.py
@@ -77,6 +77,7 @@ def add_mimedb_data(mimedb):
     add_mimetype(mimedb, 'audio/x-shn', '.shn')
     add_mimetype(mimedb, 'audio/flac', '.flac')
     add_mimetype(mimedb, 'application/x-chm', '.chm')
+    add_mimetype(mimedb, 'application/x-iso9660-image', '.iso')
 
 
 def add_mimetype(mimedb, mimetype, extension):