diff --git a/apps/readest-app/src/hooks/useSync.ts b/apps/readest-app/src/hooks/useSync.ts
index d9156ea6..66b11f9b 100644
--- a/apps/readest-app/src/hooks/useSync.ts
+++ b/apps/readest-app/src/hooks/useSync.ts
@@ -65,7 +65,8 @@ export function useSync(bookKey?: string) {
   const { syncClient } = useSyncContext();
 
   useEffect(() => {
-    setIsSyncing(bookKey || '', syncing);
+    if (!bookKey) return;
+    setIsSyncing(bookKey, syncing);
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [bookKey, syncing]);
 
diff --git a/apps/readest-app/src/store/readerStore.ts b/apps/readest-app/src/store/readerStore.ts
index 615cbd02..abd8943d 100644
--- a/apps/readest-app/src/store/readerStore.ts
+++ b/apps/readest-app/src/store/readerStore.ts
@@ -98,7 +98,7 @@ export const useReaderStore = create<ReaderStore>((set, get) => ({
   getViewsById: (id: string) => {
     const { viewStates } = get();
     return Object.values(viewStates)
-      .filter((state) => state.key.startsWith(id))
+      .filter((state) => state.key && state.key.startsWith(id))
       .map((state) => state.view!);
   },