diff --git a/tornado/locale.py b/tornado/locale.py
index fdfe0afcb7e4e2d7692eee1368dffa0f8f2376f4..415b3440d0f85744078b49f8caa751542cc87e57 100644
--- a/tornado/locale.py
+++ b/tornado/locale.py
@@ -180,7 +180,7 @@ def load_gettext_translations(directory, domain):
     logging.info("Supported locales: %s", sorted(_supported_locales))
 
 
-def get_supported_locales(cls):
+def get_supported_locales():
     """Returns a list of all the supported locale codes."""
     return _supported_locales