diff --git a/src/partials/head-styles.hbs b/src/partials/head-styles.hbs
index 72cc7e5..e731b64 100644
--- a/src/partials/head-styles.hbs
+++ b/src/partials/head-styles.hbs
@@ -2,7 +2,7 @@
 !function (theme, navWidth) {
   if (theme === 'dark') document.documentElement.classList.add('dark-theme')
   if (navWidth) document.documentElement.style.setProperty('--nav-width', `${navWidth}px`)
-}(localStorage && localStorage.getItem('theme') || (matchMedia('(prefers-color-scheme: dark)') && 'dark'),
+}(localStorage && localStorage.getItem('theme') || (matchMedia('(prefers-color-scheme: dark)')?.matches && 'dark'),
   localStorage && localStorage.getItem('nav-width'))
     </script>
     <link rel="stylesheet" href="{{{uiRootPath}}}/css/site.css">
diff --git a/src/partials/header-content.hbs b/src/partials/header-content.hbs
index 43c6a5c..15f70b4 100644
--- a/src/partials/header-content.hbs
+++ b/src/partials/header-content.hbs
@@ -216,5 +216,5 @@
   if (theme === 'dark') {
     document.getElementById('switch-theme-checkbox').parentElement.classList.add('active')
   }
-}(localStorage && localStorage.getItem('theme') || (matchMedia('(prefers-color-scheme: dark)') && 'dark'))
+}(localStorage && localStorage.getItem('theme') || (matchMedia('(prefers-color-scheme: dark)')?.matches && 'dark'))
 </script>