diff --git a/newspaper/source.py b/newspaper/source.py
index 9cc7174b..c371511c 100644
--- a/newspaper/source.py
+++ b/newspaper/source.py
@@ -305,7 +305,8 @@ def generate_articles(self, limit=5000):
         """
         articles = self._generate_articles()
         self.articles = articles[:limit]
-        log.debug(len(articles), 'articles generated and cutoff at', limit)
+        log.debug('%d articles generated and cutoff at %d',
+                  len(articles), limit)
 
     def download_articles(self, threads=1):
         """Downloads all articles attached to self