diff --git a/doc/admin.rst b/doc/admin.rst
index 9e90df8590902f28d8b1cc101803ed59dbbfcff2..3daf408650221995f4acc9ff0d8e49042d076a7e 100644
--- a/doc/admin.rst
+++ b/doc/admin.rst
@@ -542,7 +542,7 @@ 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 565b22a3533388a69d4b4c9c1e05ebdc9aadd585..827d8227fd2978f0d9db53fc6bc30dff8141dd26 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>