diff --git a/ecosystem/plugin-theme-data/src/client/composables/useThemeLocaleData.ts b/ecosystem/plugin-theme-data/src/client/composables/useThemeLocaleData.ts
index 9683c056bd..23a375a22b 100644
--- a/ecosystem/plugin-theme-data/src/client/composables/useThemeLocaleData.ts
+++ b/ecosystem/plugin-theme-data/src/client/composables/useThemeLocaleData.ts
@@ -26,7 +26,11 @@ export const useThemeLocaleData = <
 export const resolveThemeLocaleData = (
   theme: ThemeData,
   routeLocale: RouteLocale
-): ThemeData => ({
-  ...theme,
-  ...theme.locales?.[routeLocale],
-})
+): ThemeData => {
+  const { locales, ...baseOptions } = theme
+
+  return {
+    ...baseOptions,
+    ...locales?.[routeLocale],
+  }
+}