diff --git a/types/tinymce/index.d.ts b/types/tinymce/index.d.ts
index af74adf671..2791871593 100644
--- a/types/tinymce/index.d.ts
+++ b/types/tinymce/index.d.ts
@@ -358,7 +358,7 @@ export class Editor extends util.Observable {
 
   undoManager: UndoManager;
 
-  WindowManager: WindowManager;
+  windowManager: WindowManager;
 
   addButton(name: string, settings: {}): void;