diff --git a/addons/mail/static/src/components/chat_window_header/chat_window_header.js b/addons/mail/static/src/components/chat_window_header/chat_window_header.js
index 0637391ca46..d1ef7d6ea10 100644
--- a/addons/mail/static/src/components/chat_window_header/chat_window_header.js
+++ b/addons/mail/static/src/components/chat_window_header/chat_window_header.js
@@ -21,16 +21,6 @@ export class ChatWindowHeader extends Component {
         return this.messaging && this.messaging.models['ChatWindow'].get(this.props.chatWindowLocalId);
     }
 
-    /**
-     * @returns {string}
-     */
-    get shiftPrevText() {
-        if (this.messaging.locale.textDirection === 'rtl') {
-            return this.env._t("Shift right");
-        }
-        return this.env._t("Shift left");
-    }
-
     //--------------------------------------------------------------------------
     // Handlers
     //--------------------------------------------------------------------------
diff --git a/addons/mail/static/src/components/chat_window_header/chat_window_header.xml b/addons/mail/static/src/components/chat_window_header/chat_window_header.xml
index e8bc331fc15..abe340c374e 100644
--- a/addons/mail/static/src/components/chat_window_header/chat_window_header.xml
+++ b/addons/mail/static/src/components/chat_window_header/chat_window_header.xml
@@ -56,7 +56,7 @@
                         </div>
                     </t>
                     <t t-if="chatWindow.hasShiftPrev">
-                        <div class="o_ChatWindowHeader_command o_ChatWindowHeader_commandShiftPrev" t-att-class="{ 'o-mobile': messaging.device.isMobile }" t-on-click="_onClickShiftPrev" t-att-title="shiftPrevText">
+                        <div class="o_ChatWindowHeader_command o_ChatWindowHeader_commandShiftPrev" t-att-class="{ 'o-mobile': messaging.device.isMobile }" t-on-click="_onClickShiftPrev" t-att-title="chatWindow.shiftPrevText">
                             <!-- this is reversed automatically when language is rtl -->
                             <i class="fa fa-angle-left"/>
                         </div>
diff --git a/addons/mail/static/src/models/chat_window/chat_window.js b/addons/mail/static/src/models/chat_window/chat_window.js
index f5636257b67..9c3661fff0f 100644
--- a/addons/mail/static/src/models/chat_window/chat_window.js
+++ b/addons/mail/static/src/models/chat_window/chat_window.js
@@ -303,6 +303,16 @@ registerModel({
             }
             return this.env._t("Shift right");
         },
+        /**
+         * @private
+         * @returns {string}
+         */
+        _computeShiftPrevText() {
+            if (this.messaging.locale.textDirection === 'rtl') {
+                return this.env._t("Shift right");
+            }
+            return this.env._t("Shift left");
+        },
         /**
          * @private
          * @returns {ThreadViewer}
@@ -489,6 +499,9 @@ registerModel({
         shiftNextText: attr({
             compute: '_computeShiftNextText',
         }),
+        shiftPrevText: attr({
+            compute: '_computeShiftPrevText',
+        }),
         /**
          * Determines the `Thread` that should be displayed by `this`.
          * If no `Thread` is linked, `this` is considered "new message".