diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 31e64a21470..e5ffba0d2cc 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -134,7 +134,7 @@ Number-theoretic and representation functions
 .. function:: trunc(x)
 
    Return the :class:`Real` value *x* truncated to an :class:`Integral` (usually
-   a long integer).
+   a long integer).  Uses the ``__trunc__`` method.
 
    .. versionadded:: 2.6