diff --git a/widget/windows/WinEventObserver.cpp b/widget/windows/WinEventObserver.cpp
index 90300e941290..c302b8dba06a 100644
--- a/widget/windows/WinEventObserver.cpp
+++ b/widget/windows/WinEventObserver.cpp
@@ -4,7 +4,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include <corecrt_memcpy_s.h>
 #include <windows.h>
 #include <winternl.h>
 #include <winuser.h>