diff --git a/nuxt/components/modal/EditBookRecommendation.vue b/nuxt/components/modal/EditBookRecommendation.vue
index a86c48e..c624b41 100644
--- a/nuxt/components/modal/EditBookRecommendation.vue
+++ b/nuxt/components/modal/EditBookRecommendation.vue
@@ -114,6 +114,10 @@ async function onSubmit(event: FormSubmitEvent<any>) {
   })
   await bookRecommendationStore.fetchRecommendations()
 }
+
+function isFile(value: any): value is File {
+  return value instanceof File
+}
 </script>
 
 <template>
@@ -145,7 +149,7 @@ async function onSubmit(event: FormSubmitEvent<any>) {
             <UTextarea v-model="state.description" />
           </UFormGroup>
           <img v-if="state.cover_image && typeof state.cover_image === 'string'" :src="$storage(state.cover_image)" alt="Cover" class="size-1/3 content-center rounded-lg">
-          <img v-else-if="state.cover_image && state.cover_image instanceof File" :src="URL.createObjectURL(state.cover_image)" alt="Cover" class="size-1/3 content-center rounded-lg">
+          <img v-else-if="state.cover_image && isFile(state.cover_image)" :src="URL.createObjectURL(state.cover_image)" alt="Cover" class="size-1/3 content-center rounded-lg">
           <UFormGroup label="Cover" name="cover_image">
             <UInput type="file" @change="handleCoverImageInput" />
           </UFormGroup>