diff --git a/addons/hr_holidays/static/src/thread_patch.xml b/addons/hr_holidays/static/src/thread_patch.xml
index 147ea024cd8..4caaa72d16a 100644
--- a/addons/hr_holidays/static/src/thread_patch.xml
+++ b/addons/hr_holidays/static/src/thread_patch.xml
@@ -2,7 +2,7 @@
 <templates xml:space="preserve">
     <t t-inherit="mail.Thread" t-inherit-mode="extension">
         <xpath expr="//*[hasclass('o-mail-Thread')]" position="before">
-            <div t-if="props.thread.model === 'discuss.channel' and props.thread.correspondent and personaService.outOfOfficeText(props.thread.correspondent)" class="alert alert-primary" t-esc="personaService.outOfOfficeText(props.thread.correspondent)" role="alert"/>
+            <div t-if="props.thread.model === 'discuss.channel' and props.thread.correspondent and personaService.outOfOfficeText(props.thread.correspondent)" class="alert alert-primary rounded-0" t-esc="personaService.outOfOfficeText(props.thread.correspondent)" role="alert"/>
         </xpath>
     </t>
 </templates>