diff --git a/lib/libc/sys/mprotect.2 b/lib/libc/sys/mprotect.2
index 5c024dd24d56..c2c7701d624e 100644
--- a/lib/libc/sys/mprotect.2
+++ b/lib/libc/sys/mprotect.2
@@ -1,124 +1,131 @@
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 .\"    may be used to endorse or promote products derived from this software
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 .\"
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 .\"	@(#)mprotect.2	8.1 (Berkeley) 6/9/93
 .\" $FreeBSD$
 .\"
-.Dd September 3, 2021
+.Dd September 7, 2021
 .Dt MPROTECT 2
 .Os
 .Sh NAME
 .Nm mprotect
 .Nd control the protection of pages
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In sys/mman.h
 .Ft int
 .Fn mprotect "void *addr" "size_t len" "int prot"
 .Sh DESCRIPTION
 The
 .Fn mprotect
 system call
 changes the specified pages to have protection
 .Fa prot .
 .Pp
-Currently these protection bits are known,
-which can be combined, OR'd together:
+The
+.Fa prot
+argument shall be
+.Dv PROT_NONE
+(no permissions at all)
+or the bitwise
+.Em or
+of one or more of the following values:
 .Pp
 .Bl -tag -width ".Dv PROT_WRITE" -compact
-.It Dv PROT_NONE
-No permissions at all.
 .It Dv PROT_READ
 The pages can be read.
 .It Dv PROT_WRITE
 The pages can be written.
 .It Dv PROT_EXEC
 The pages can be executed.
 .El
 .Pp
-In addition to these protection flags,
+In addition to these standard protection flags,
+the
 .Fx
+implementation of
+.Fn mprotect
 provides the ability to set the maximum protection of a region
 (which prevents
 .Nm
-from upgrading the permissions).
-This is accomplished by
+from adding to the permissions later).
+This is accomplished by bitwise
 .Em or Ns 'ing
 one or more
 .Dv PROT_
 values wrapped in the
 .Dv PROT_MAX()
 macro into the
 .Fa prot
 argument.
 .Sh RETURN VALUES
 .Rv -std mprotect
 .Sh ERRORS
 The
 .Fn mprotect
 system call will fail if:
 .Bl -tag -width Er
 .It Bq Er EACCES
 The calling process was not allowed to change
 the protection to the value specified by
 the
 .Fa prot
 argument.
 .It Bq Er EINVAL
 The virtual address range specified by the
 .Fa addr
 and
 .Fa len
 arguments is not valid.
 .It Bq Er EINVAL
 The
 .Fa prot
 argument contains unhandled bits.
 .It Bq Er ENOTSUP
 The
 .Fa prot
 argument contains permissions which are not a subset of the specified
 maximum permissions.
 .El
 .Sh SEE ALSO
 .Xr madvise 2 ,
 .Xr mincore 2 ,
 .Xr msync 2 ,
 .Xr munmap 2
 .Sh HISTORY
 The
 .Fn mprotect
 system call was first documented in
 .Bx 4.2
 and first appeared in
 .Bx 4.4 .
 .Pp
 The
 .Dv PROT_MAX
 functionality was introduced in
 .Fx 13 .