diff --git a/oletools/msodde.py b/oletools/msodde.py
index bd1e7f5..306104e 100644
--- a/oletools/msodde.py
+++ b/oletools/msodde.py
@@ -722,6 +722,7 @@ def process_xlsx(filepath, filed_filter_mode=None):
 def process_file(filepath, field_filter_mode=None):
     """ decides which of process_doc/x or process_xls/x to call """
     if olefile.isOleFile(filepath):
+        log.debug('checking streams to see whether this is xls')
         if xls_parser.is_xls(filepath):
             return process_xls(filepath)
         else:
diff --git a/oletools/xls_parser.py b/oletools/xls_parser.py
index f032dd6..30f7840 100644
--- a/oletools/xls_parser.py
+++ b/oletools/xls_parser.py
@@ -390,6 +390,7 @@ def test(*filenames):
     for filename in filenames:
         logging.info('checking file {0}'.format(filename))
         if not olefile.isOleFile(filename):
+            logging.info('not an ole file - skip')
             continue
         xls = XlsFile(filename)