diff --git a/doc/admin.rst b/doc/admin.rst
index 1918dbe3b74a98286bca0aba5c825886c06e2953..99ccb8375db9eb59456be21264fc45dc90515610 100644
--- a/doc/admin.rst
+++ b/doc/admin.rst
@@ -526,7 +526,7 @@ modify`` command::
 
   # later convert it to redundant
   gnt-instance stop INSTANCE
-  gnt-instance modify -t drbd INSTANCE
+  gnt-instance modify -t drbd -n NEW_SECONDARY INSTANCE
   gnt-instance start INSTANCE
 
   # and convert it back
diff --git a/man/gnt-instance.sgml b/man/gnt-instance.sgml
index bddd8d24ad35860bf06ac8ac7165c5e455c7cb06..abaef12660dba9eb24df74a001750a1f36e7ce9f 100644
--- a/man/gnt-instance.sgml
+++ b/man/gnt-instance.sgml
@@ -1585,7 +1585,10 @@ instance5: 11225
           The <option>-t</option> option will change the disk template
           of the instance. Currently only conversions between the
           plain and drbd disk templates are supported, and the
-          instance must be stopped before attempting the conversion.
+          instance must be stopped before attempting the
+          conversion. When changing from the plain to the drbd disk
+          template, a new secondary node must be specified via
+          the <option>-n</option> option.
         </para>
 
         <para>