diff --git a/man/gnt-backup.sgml b/man/gnt-backup.sgml
index 66d4301138fff2d06ddc58a4273c297aa687a57e..8d4943bf12281f47fc2c9d2ca431d58f0df3b9df 100644
--- a/man/gnt-backup.sgml
+++ b/man/gnt-backup.sgml
@@ -94,6 +94,7 @@
         <command>import</command>
         <arg choice="req">-n <replaceable>node<optional>:secondary-node</optional></replaceable></arg>
         <arg>-s <replaceable>disksize</replaceable></arg>
+        <arg>--swap-size <replaceable>disksize</replaceable></arg>
         <arg>-m <replaceable>memsize</replaceable></arg>
         <arg>-b <replaceable>bridge</replaceable></arg>
         <sbr>
@@ -129,6 +130,14 @@
         these suffixes map to mebibytes, gibibytes and tebibytes.
       </para>
 
+      <para>
+        The <option>--swap-size</option> option specifies the swap
+        disk size (in mebibytes) for the instance (the one presented
+        as <filename class="devicefile">/dev/sdb</filename>). The
+        default is <constant>4096MiB</constant>. As for the disk
+        size, you can specify other suffixes.
+      </para>
+
       <para>
         The <option>-m</option> option specifies the memory size for
         the instance, in mebibytes (defaults to 128 MiB).