diff --git a/purchase.xml b/purchase.xml
index b0e2b26247..b4b5fd1a66 100644
--- a/purchase.xml
+++ b/purchase.xml
@@ -86,7 +86,7 @@ this repository contains the full copyright notices and license terms. -->
                                         states="{'invisible': '''state != 'quotation' ''', 'readonly': '''%(group_purchase)d not in groups'''}"
                                         icon="tryton-go-previous"/>
                                     <button name="quotation" string="Quotation"
-                                        states="{'invisible': '''state != 'draft' ''', 'readonly': '''%(group_purchase)d not in groups'''}"
+                                        states="{'invisible': '''state != 'draft' ''', 'readonly': '''(not bool(lines)) or %(group_purchase)d not in groups '''}"
                                         icon="tryton-go-next"/>
                                     <button name="%(wizard_invoice_handle_exception)d"
                                             string="Handle Invoice Exception"
@@ -464,6 +464,7 @@ this repository contains the full copyright notices and license terms. -->
         <record model="workflow.transition" id="purchase_transition_draft_quotation">
             <field name="act_from" ref="purchase_activity_draft"/>
             <field name="act_to" ref="purchase_activity_quotation"/>
+            <field name="condition">bool(lines)</field>
             <field name="signal">quotation</field>
             <field name="group" ref="group_purchase"/>
         </record>