diff --git a/src/calibre/gui2/auto_add.py b/src/calibre/gui2/auto_add.py
index c49ca87bf6..74c3ec2bdd 100644
--- a/src/calibre/gui2/auto_add.py
+++ b/src/calibre/gui2/auto_add.py
@@ -26,7 +26,7 @@ class Worker(Thread):
         self.wake_up = Event()
         self.path, self.callback = path, callback
         self.staging = set()
-        self.be = frozenset(BOOK_EXTENSIONS)
+        self.be = frozenset(BOOK_EXTENSIONS) - {'pdr', 'mbp', 'tan'}
 
     def run(self):
         self.tdir = PersistentTemporaryDirectory('_auto_adder')