diff --git a/Lib/ConfigParser.py b/Lib/ConfigParser.py
index 6cf3c2a..963a418 100644
--- a/Lib/ConfigParser.py
+++ b/Lib/ConfigParser.py
@@ -570,7 +570,7 @@
     def keys(self):
         result = []
         seen = set()
-        for mapping in self_maps:
+        for mapping in self._maps:
             for key in mapping:
                 if key not in seen:
                     result.append(key)