diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index 16429de..d612e87 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -270,8 +270,12 @@
 
 .. method:: timedelta.total_seconds()
 
-   Return the total number of seconds contained in the duration. Equivalent to
-   ``td.microseconds / 1000000 + td.seconds + td.days * 24 * 3600``.
+   Return the total number of seconds contained in the duration.
+   Equivalent to ``(td.microseconds + (td.seconds + td.days * 24 *
+   3600) * 10**6) / 10**6`` computed with true division enabled.
+
+   Note that for very large time intervals (greater than 270 years on
+   most platforms) this method will lose microsecond accuracy.
 
    .. versionadded:: 2.7