diff --git a/pandora_client/__init__.py b/pandora_client/__init__.py
index 530a371..e1f6edd 100755
--- a/pandora_client/__init__.py
+++ b/pandora_client/__init__.py
@@ -371,9 +371,10 @@ class Client(object):
             sql = u'SELECT oshash FROM encode WHERE site = ?'
             c.execute(sql, (site, ))
             known = [row[0] for row in c]
-            files = list(set(files) - set(known))
             conn.close()
-            self.add_encodes(site, files)
+            files = list(set(files) - set(known))
+            if files:
+                self.add_encodes(site, files)
         else:
             self.set_encodes(site, files)