diff --git a/stdlib/2and3/logging/__init__.pyi b/stdlib/2and3/logging/__init__.pyi
index 744057261..9e2a7d9e0 100644
--- a/stdlib/2and3/logging/__init__.pyi
+++ b/stdlib/2and3/logging/__init__.pyi
@@ -186,6 +186,7 @@ class Formatter:
     def formatTime(self, record: LogRecord, datefmt: str = ...) -> str: ...
     def formatException(self, exc_info: _SysExcInfoType) -> str: ...
     if sys.version_info >= (3,):
+        def formatMessage(self, record: LogRecord) -> str: ...  # undocumented
         def formatStack(self, stack_info: str) -> str: ...