diff --git a/oletools/ppt_parser.py b/oletools/ppt_parser.py
index 4f01b1a..450ded2 100644
--- a/oletools/ppt_parser.py
+++ b/oletools/ppt_parser.py
@@ -1125,7 +1125,7 @@ class PptParser(object):
             log.debug('using open OleFileIO')
             self.ole = ole
         else:
-            log.debug('Opening file ' + ole)
+            log.debug('Opening file {0}'.format(ole))
             self.ole = olefile.OleFileIO(ole)
 
         self.fast_fail = fast_fail