diff --git a/packages/use-theme/src/use-theme.ts b/packages/use-theme/src/use-theme.ts
index c6ce2c7c..5d3ae2a0 100644
--- a/packages/use-theme/src/use-theme.ts
+++ b/packages/use-theme/src/use-theme.ts
@@ -49,6 +49,8 @@ export function useTheme(options?: UseThemeOptions): UseThemeReturn {
 
   // Sync across tabs via storage event
   useEffect(() => {
+    if (typeof window === 'undefined') return;
+
     function handleStorage(event: StorageEvent) {
       if (event.key !== storageKey) {
         return;
@@ -65,7 +67,9 @@ export function useTheme(options?: UseThemeOptions): UseThemeReturn {
   const setTheme = useCallback(
     (t: Theme) => {
       setThemeState(t);
-      window.localStorage.setItem(storageKey, t);
+      if (typeof window !== 'undefined') {
+        window.localStorage.setItem(storageKey, t);
+      }
     },
     [storageKey]
   );
@@ -73,7 +77,9 @@ export function useTheme(options?: UseThemeOptions): UseThemeReturn {
   const toggleTheme = useCallback(() => {
     setThemeState(prev => {
       const next: Theme = prev === 'dark' ? 'light' : 'dark';
-      window.localStorage.setItem(storageKey, next);
+      if (typeof window !== 'undefined') {
+        window.localStorage.setItem(storageKey, next);
+      }
       applyTheme(next, attribute);
       return next;
     });