diff --git a/Doc/library/time.rst b/Doc/library/time.rst
index 2782a961363666..dedd4a7e8fc73d 100644
--- a/Doc/library/time.rst
+++ b/Doc/library/time.rst
@@ -314,7 +314,8 @@ Functions
    clock with the highest available resolution to measure a short duration.  It
    does include time elapsed during sleep and is system-wide.  The reference
    point of the returned value is undefined, so that only the difference between
-   the results of two calls is valid.
+   the results of two calls is valid. This counter, like :func:`monotonic`, cannot
+   go backwards.
 
    Use :func:`perf_counter_ns` to avoid the precision loss caused by the
    :class:`float` type.