diff --git a/manpages/shorewall-interfaces.xml b/manpages/shorewall-interfaces.xml
index c09355a2a..256e2e953 100644
--- a/manpages/shorewall-interfaces.xml
+++ b/manpages/shorewall-interfaces.xml
@@ -349,7 +349,7 @@ loc     eth2            -</programlisting>
 
             <varlistentry>
               <term><emphasis
-              role="bold">mss</emphasis>[=<emphasis>number</emphasis>]</term>
+              role="bold">mss</emphasis>=<emphasis>number</emphasis></term>
 
               <listitem>
                 <para>Added in Shorewall 4.0.3. Causes forwarded TCP SYN
diff --git a/manpages6/shorewall6-interfaces.xml b/manpages6/shorewall6-interfaces.xml
index d0f59b07f..7989ff702 100644
--- a/manpages6/shorewall6-interfaces.xml
+++ b/manpages6/shorewall6-interfaces.xml
@@ -133,7 +133,7 @@ loc     eth2            -</programlisting>
 
             <varlistentry>
               <term><emphasis
-              role="bold">mss</emphasis>[=<emphasis>number</emphasis>]</term>
+              role="bold">mss</emphasis>=<emphasis>number</emphasis></term>
 
               <listitem>
                 <para>Causes forwarded TCP SYN packets entering or leaving on