diff --git a/stdlib/optparse.pyi b/stdlib/optparse.pyi
index c32a17ceb..65386131f 100644
--- a/stdlib/optparse.pyi
+++ b/stdlib/optparse.pyi
@@ -1,3 +1,4 @@
+from abc import abstractmethod
 from typing import IO, Any, AnyStr, Callable, Iterable, Mapping, Sequence, overload
 
 NO_DEFAULT: tuple[str, ...]
@@ -47,9 +48,11 @@ class HelpFormatter:
     def expand_default(self, option: Option) -> str: ...
     def format_description(self, description: str) -> str: ...
     def format_epilog(self, epilog: str) -> str: ...
+    @abstractmethod
     def format_heading(self, heading: Any) -> str: ...
     def format_option(self, option: Option) -> str: ...
     def format_option_strings(self, option: Option) -> str: ...
+    @abstractmethod
     def format_usage(self, usage: Any) -> str: ...
     def indent(self) -> None: ...
     def set_long_opt_delimiter(self, delim: str) -> None: ...