diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index cba5757a5..6088f71b0 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -237,7 +237,8 @@ class Throttled(APIException):
         self.wait = wait
         super().__init__(detail, code)
 
-    def extra_detail(self, wait):
+    @staticmethod
+    def extra_detail(wait):
         return ngettext(
             'Expected available in {wait} second.',
             'Expected available in {wait} seconds.',