diff --git a/Shorewall/Perl/Shorewall/Nat.pm b/Shorewall/Perl/Shorewall/Nat.pm
index aea2af77b..8cf61ce32 100644
--- a/Shorewall/Perl/Shorewall/Nat.pm
+++ b/Shorewall/Perl/Shorewall/Nat.pm
@@ -378,7 +378,7 @@ sub process_one_masq1( $$$$$$$$$$$ )
 
 sub process_one_masq( )
 {
-    my ($interfacelist, $networks, $addresses, $protos, $ports, $ipsec, $mark, $user, $condition, $origdest ) =
+    my ($interfacelist, $networks, $addresses, $protos, $ports, $ipsec, $mark, $user, $condition, $origdest, $probability ) =
 	split_line2( 'masq file',
 		     { interface => 0, source => 1, address => 2, proto => 3, port => 4, ipsec => 5, mark => 6, user => 7, switch => 8, origdest => 9, probability => 10 },
 		     {},    #Nopad
@@ -388,7 +388,7 @@ sub process_one_masq( )
     fatal_error 'INTERFACE must be specified' if $interfacelist eq '-';
 
     for my $proto ( split_list $protos, 'Protocol' ) {
-	process_one_masq1( $interfacelist, $networks, $addresses, $proto, $ports, $ipsec, $mark, $user, $condition, $origdest );
+	process_one_masq1( $interfacelist, $networks, $addresses, $proto, $ports, $ipsec, $mark, $user, $condition, $origdest, $probability );
     }
 }
 
diff --git a/Shorewall/manpages/shorewall-masq.xml b/Shorewall/manpages/shorewall-masq.xml
index cb59f2d98..3d5c7bc82 100644
--- a/Shorewall/manpages/shorewall-masq.xml
+++ b/Shorewall/manpages/shorewall-masq.xml
@@ -552,6 +552,21 @@
           that were acted on by a DNAT when they entered the firewall.</para>
         </listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><emphasis role="bold">PROBABILITY</emphasis> -
+        [<replaceable>probability</replaceable>]</term>
+
+        <listitem>
+          <para>Added in Shorewall 5.0.0. When non-empty, requires the
+          <firstterm>Statistics Match</firstterm> capability in your kernel
+          and ip6tables and causes the rule to match randomly but with the
+          given <replaceable>probability</replaceable>. The
+          <replaceable>probability</replaceable> is a number 0 &lt;
+          <replaceable>probability</replaceable> &lt;= 1 and may be expressed
+          at up to 8 decimal points of precision.</para>
+        </listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 
diff --git a/Shorewall6/manpages/shorewall6-masq.xml b/Shorewall6/manpages/shorewall6-masq.xml
index 54ad6afb2..036dfc727 100644
--- a/Shorewall6/manpages/shorewall6-masq.xml
+++ b/Shorewall6/manpages/shorewall6-masq.xml
@@ -502,6 +502,21 @@
           entered the firewall.</para>
         </listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><emphasis role="bold">PROBABILITY</emphasis> -
+        [<replaceable>probability</replaceable>]</term>
+
+        <listitem>
+          <para>Added in Shorewall 5.0.0. When non-empty, requires the
+          <firstterm>Statistics Match</firstterm> capability in your kernel
+          and ip6tables and causes the rule to match randomly but with the
+          given <replaceable>probability</replaceable>. The
+          <replaceable>probability</replaceable> is a number 0 &lt;
+          <replaceable>probability</replaceable> &lt;= 1 and may be expressed
+          at up to 8 decimal points of precision.</para>
+        </listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>