diff --git a/src/components/ThemeSwitcher.astro b/src/components/ThemeSwitcher.astro
index 25b1796..d748a91 100644
--- a/src/components/ThemeSwitcher.astro
+++ b/src/components/ThemeSwitcher.astro
@@ -11,7 +11,7 @@ interface Props extends HTMLAttributes<"div"> {
   darkBgClass?: string[];
   lightBgClass?: string[];
   rootExtraClass?: string;
-  onChange?: (mode: "light" | "dark" | "system") => void;
+  onChange?: string;
 }
 
 const {
@@ -23,7 +23,7 @@ const {
   lightBgClass = [],
   rootExtraClass = "",
   class: className,
-  onChange,
+  onChange = "onThemeChange",
   ...rest
 }: Props = Astro.props;
 
@@ -140,7 +140,8 @@ const checkBase = "wr:size-4 wr:opacity-0 wr:scale-90 wr:transition";
     localStorage.setItem(storageKey, mode);
     reflectUI(mode);
 
-    onChange?.(mode);
+    const fn  = window[onChange];
+    if (typeof fn === "function") fn(mode);
   }
 
   // Init