diff --git a/app/src/protyle/scroll/event.ts b/app/src/protyle/scroll/event.ts
index a42fbf923..c4182efce 100644
--- a/app/src/protyle/scroll/event.ts
+++ b/app/src/protyle/scroll/event.ts
@@ -28,10 +28,12 @@ export const scrollEvent = (protyle: IProtyle, element: HTMLElement) => {
             if (item.parentElement.classList.contains("protyle-wysiwyg")) {
                 const headerTop = item.offsetTop - 30 + 56
                 const headerElement = item.querySelector(".av__row--header") as HTMLElement
-                if (headerTop < element.scrollTop && headerTop + headerElement.parentElement.clientHeight > element.scrollTop) {
-                    headerElement.style.transform = `translateY(${element.scrollTop - headerTop}px)`;
-                } else {
-                    headerElement.style.transform = "";
+                if (headerElement) {
+                    if (headerTop < element.scrollTop && headerTop + headerElement.parentElement.clientHeight > element.scrollTop) {
+                        headerElement.style.transform = `translateY(${element.scrollTop - headerTop}px)`;
+                    } else {
+                        headerElement.style.transform = "";
+                    }
                 }
             }
         });