diff --git a/README.md b/README.md
index 52766e4..9460c6b 100644
--- a/README.md
+++ b/README.md
@@ -14,8 +14,9 @@ npm install astro-theme-toggle
 
 ## Usage
 
-1. Add the `ThemeScript` component to your `<head>`. This will toggle the `dark`
-   class on your `<html>` element based on the user's theme preference.
+1. Add the `ThemeScript` component to your `<head>`. This will set the
+   `data-theme` attribute and toggle the `dark` class on your `<html>` element
+   based on the user's theme preference.
 
    ```astro
    ---
diff --git a/lib/theme-script.astro b/lib/theme-script.astro
index a77ea54..41d4dbc 100644
--- a/lib/theme-script.astro
+++ b/lib/theme-script.astro
@@ -1,4 +1,4 @@
 
 <script is:inline>
-"use strict";(()=>{(()=>{let t="theme-toggle";function o(){return window.matchMedia("(prefers-color-scheme: dark)").matches?"dark":"light"}function c(){let e=localStorage.getItem(t);return e==="dark"||e==="light"?e:null}function n(){return c()||o()}function l(e){e===o()?localStorage.removeItem(t):localStorage.setItem(t,e)}function a(e){let s=document.documentElement;s.classList.toggle("dark",e==="dark"),s.style.colorScheme=e}function r(e){l(e),a(e)}function m(){r(n())}m(),document.addEventListener("astro:after-swap",m),window.astroThemeToggle={setTheme:r,getTheme:n}})();})();
+"use strict";(()=>{(()=>{let t="theme-toggle";function n(){return window.matchMedia("(prefers-color-scheme: dark)").matches?"dark":"light"}function a(){let e=localStorage.getItem(t);return e==="dark"||e==="light"?e:null}function r(){return a()||n()}function c(e){e===n()?localStorage.removeItem(t):localStorage.setItem(t,e)}function l(e){let o=document.documentElement;o.classList.toggle("dark",e==="dark"),o.dataset.theme=e,o.style.colorScheme=e}function m(e){c(e),l(e)}function s(){m(r())}s(),document.addEventListener("astro:after-swap",s),window.astroThemeToggle={setTheme:m,getTheme:r}})();})();
 </script>
diff --git a/lib/theme-script.ts b/lib/theme-script.ts
index 4e6a535..97de560 100644
--- a/lib/theme-script.ts
+++ b/lib/theme-script.ts
@@ -29,6 +29,7 @@
   function setStyle(theme: Theme) {
     const root = document.documentElement
     root.classList.toggle('dark', theme === 'dark')
+    root.dataset.theme = theme
     root.style.colorScheme = theme
   }
 
