diff --git a/.devcontainer/ui-lovelace.yaml b/.devcontainer/ui-lovelace.yaml
index 096d926..2b3d5cc 100644
--- a/.devcontainer/ui-lovelace.yaml
+++ b/.devcontainer/ui-lovelace.yaml
@@ -92,6 +92,8 @@ views:
               floating: true
 
           - type: custom:apexcharts-card
+            show:
+              last_updated: true
             update_interval: 2s
             stacked: true
             experimental:
diff --git a/src/apexcharts-card.ts b/src/apexcharts-card.ts
index ea01fe8..2323dbb 100644
--- a/src/apexcharts-card.ts
+++ b/src/apexcharts-card.ts
@@ -24,6 +24,7 @@ import {
   decompress,
   getPercentFromValue,
   interpolateColor,
+  is12Hour,
   log,
   mergeConfigTemplates,
   mergeDeep,
@@ -686,9 +687,7 @@ class ChartsCard extends LitElement {
     if (this._config?.show?.last_updated) {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       let hours12: any = undefined;
-      if (this._config.hours_12 !== undefined) {
-        hours12 = this._config.hours_12 ? { hour12: true } : { hourCycle: 'h23' };
-      }
+      hours12 = is12Hour(this._config, this._hass) ? { hour12: true } : { hourCycle: 'h23' };
       const lastUpdated = new Intl.DateTimeFormat(this._config.locale || this._hass?.language || 'en', {
         year: 'numeric',
         month: 'short',