diff --git a/lib/libc/sys/sigaction.2 b/lib/libc/sys/sigaction.2
index 59c99c511109..f7158e23abed 100644
--- a/lib/libc/sys/sigaction.2
+++ b/lib/libc/sys/sigaction.2
@@ -28,7 +28,7 @@
 .\"	From: @(#)sigaction.2	8.2 (Berkeley) 4/3/94
 .\" $FreeBSD$
 .\"
-.Dd September 30, 2016
+.Dd June 28, 2018
 .Dt SIGACTION 2
 .Os
 .Sh NAME
@@ -46,6 +46,7 @@ struct  sigaction {
         sigset_t sa_mask;               /* signal mask to apply */
 };
 .Ed
+.Pp
 .Ft int
 .Fo sigaction
 .Fa "int sig"
@@ -143,15 +144,13 @@ assigns an action for a signal specified by
 .Fa sig .
 If
 .Fa act
-is non-zero, it
-specifies an action
+is non-NULL, it specifies an action
 .Dv ( SIG_DFL ,
 .Dv SIG_IGN ,
-or a handler routine) and mask
-to be used when delivering the specified signal.
+or a handler routine) and mask to be used when delivering the specified signal.
 If
 .Fa oact
-is non-zero, the previous handling information for the signal
+is non-NULL, the previous handling information for the signal
 is returned to the user.
 .Pp
 The above declaration of
@@ -161,8 +160,12 @@ It is provided only to list the accessible members.
 See
 .In sys/signal.h
 for the actual definition.
-In particular, the storage occupied by sa_handler and sa_sigaction overlaps,
-and an application can not use both simultaneously.
+In particular, the storage occupied by
+.Va sa_handler
+and
+.Va sa_sigaction
+overlaps, and it is nonsensical for an application to attempt to use both
+simultaneously.
 .Pp
 Once a signal handler is installed, it normally remains installed
 until another