diff --git a/seaborn/_core/scales.py b/seaborn/_core/scales.py
index 9536b1fecc..a3cdfb28f6 100644
--- a/seaborn/_core/scales.py
+++ b/seaborn/_core/scales.py
@@ -73,7 +73,7 @@ def label(self):
     def _get_locators(self):
         raise NotImplementedError()
 
-    def _get_formatter(self):
+    def _get_formatter(self, locator: Locator | None = None):
         raise NotImplementedError()
 
     def _get_scale(self, name: str, forward: Callable, inverse: Callable):