diff --git a/man2/clock_nanosleep.2 b/man2/clock_nanosleep.2
index e7047b928..41b94dd0b 100644
--- a/man2/clock_nanosleep.2
+++ b/man2/clock_nanosleep.2
@@ -87,6 +87,11 @@ since some unspecified point in the past that does not change after
 system startup.
 .\" On Linux this clock measures time since boot.
 .TP
+.BR CLOCK_BOOTIME " (since Linux 2.6.39)"
+Identical to
+.BR CLOCK_MONOTONIC ,
+except that it also includes any time that the system is suspended.
+.TP
 .BR CLOCK_PROCESS_CPUTIME_ID
 A settable per-process clock that measures CPU time consumed
 by all threads in the process.