diff --git a/trytond/ir/view/model_button_rule_form.xml b/trytond/ir/view/model_button_rule_form.xml
index af38b4e704..f82b648c3f 100644
--- a/trytond/ir/view/model_button_rule_form.xml
+++ b/trytond/ir/view/model_button_rule_form.xml
@@ -12,5 +12,5 @@ this repository contains the full copyright notices and license terms. -->
     <label name="group"/>
     <field name="group"/>
     <label name="condition"/>
-    <field name="condition" colspan="3"/>
+    <field name="condition" colspan="3" widget="pyson"/>
 </form>