diff --git a/lib/libsys/timerfd.2 b/lib/libsys/timerfd.2
index 7a112ad0dfcb..ae6cc6f6f49a 100644
--- a/lib/libsys/timerfd.2
+++ b/lib/libsys/timerfd.2
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 21, 2023
+.Dd June 28, 2024
 .Dt TIMERFD 2
 .Os
 .Sh NAME
@@ -95,9 +95,16 @@ argument specifies the clock used as a timing base and may be:
 .Bl -tag -width "Dv CLOCK_MONOTONIC" -compact
 .It Dv CLOCK_REALTIME
 Increments as a wall clock should.
+.It Dv CLOCK_BOOTTIME
 .It Dv CLOCK_MONOTONIC
 Increments monotonically in SI seconds.
+.It Dv CLOCK_UPTIME
+Increments monotonically in SI seconds, but is paused while the system is
+suspended.
 .El
+See
+.Xr clock_gettime 2
+for more precise definitions.
 .Pp
 The
 .Fa flags