diff --git a/packages/roosterjs-content-model-core/lib/coreApi/setContentModel/persistHighlight.ts b/packages/roosterjs-content-model-core/lib/coreApi/setContentModel/persistHighlight.ts
index 882c5cc0dc1..b013d86e22d 100644
--- a/packages/roosterjs-content-model-core/lib/coreApi/setContentModel/persistHighlight.ts
+++ b/packages/roosterjs-content-model-core/lib/coreApi/setContentModel/persistHighlight.ts
@@ -10,10 +10,6 @@ interface WindowWithHighlight extends Window {
     Highlight: typeof Highlight;
 }
 
-export function isWindowWithHighlight(win: Window): win is WindowWithHighlight {
-    return !!(win as WindowWithHighlight).Highlight;
-}
-
 interface HighlightRegistryWithMap extends HighlightRegistry {
     set(name: string, highlight: Highlight): void;
     delete(name: string): void;
@@ -33,6 +29,15 @@ interface CSSShim {
 
 declare const CSS: CSSShim;
 
+/**
+ * @internal
+ * @param win current window that Highlight is being used.
+ * @returns boolean indicates if Highlight api is available
+ */
+export function isWindowWithHighlight(win: Window): win is WindowWithHighlight {
+    return !!(win as WindowWithHighlight).Highlight;
+}
+
 /**
  * @internal
  * Persist highlight of a indicated selection object