diff --git a/src/calibre/ebooks/conversion/plugins/mobi_input.py b/src/calibre/ebooks/conversion/plugins/mobi_input.py
index 6c6ffb2bba..f56eb2002c 100644
--- a/src/calibre/ebooks/conversion/plugins/mobi_input.py
+++ b/src/calibre/ebooks/conversion/plugins/mobi_input.py
@@ -52,6 +52,7 @@ class MOBIInput(InputFormatPlugin):
                 mr.extract_content(u'.', parse_cache)
 
         if mr.kf8_type is not None:
+            log('Found KF8 MOBI')
             from calibre.ebooks.mobi.reader.mobi8 import Mobi8Reader
             return os.path.abspath(Mobi8Reader(mr, log)())