diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index d22cc2812dce44..ba5d2cf8033959 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -164,6 +164,8 @@ are always available.  They are listed here in alphabetical order.
    :func:`sys.breakpointhook` can be set to some other function and
    :func:`breakpoint` will automatically call that, allowing you to drop into
    the debugger of choice.
+   If :func:`sys.breakpointhook` is not available to be called, this function will
+   raise :exc:`RuntimeError`.
 
    .. audit-event:: builtins.breakpoint breakpointhook breakpoint