diff --git a/userconfig/__init__.py b/userconfig/__init__.py
index c13db7c..787188c 100644
--- a/userconfig/__init__.py
+++ b/userconfig/__init__.py
@@ -235,8 +235,8 @@ class Userconfig:
         # get temp_file and dest_file, remove comments and whitespaces
         temp_lines = self.sanitize_input(open(temp_file), comment_string)
         dest_lines = self.sanitize_input(open(dest_file), comment_string)
-        # differences of temp_file and dest_file in both directions, if > 0: files differ
-        return len(temp_lines.difference(dest_lines)) + len(dest_lines.difference(temp_lines)) != 0
+        # differences of temp_file and dest_file in both directions, if != 0: files differ
+        return len(temp_lines.symmetric_difference(dest_lines)) != 0
 
     def user_config_generated(self, filename):
         """returns True if filename has been generated by userconfig, False else"""