diff --git a/htop.1.in b/htop.1.in
index 26effeb0..a6833885 100644
--- a/htop.1.in
+++ b/htop.1.in
@@ -323,6 +323,14 @@ The size of the dirty pages of the process.
 .B M_SWAP (SWAP)
 Size of the process's swapped pages.
 .TP
+.B M_PSS (PSS)
+proportional set size, same as M_RESIDENT but each page is divided by the
+number of processes sharing it.
+.TP
+.B M_M_PSSWP (PSSWP)
+Shows proportional swap share of this mapping, unlike \fBM_SWAP\fR this does not take
+into account swapped out page of underlying shmem objects.
+.TP
 .B ST_UID (UID)
 The user ID of the process owner.
 .TP