--- a/accessible/ipc/win/HandlerProvider.h
+++ b/accessible/ipc/win/HandlerProvider.h
@@ -11,16 +11,18 @@
 #include "mozilla/AlreadyAddRefed.h"
 #include "mozilla/Atomics.h"
 #include "mozilla/mscom/IHandlerProvider.h"
 #include "mozilla/mscom/Ptr.h"
 #include "mozilla/mscom/StructStream.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/UniquePtr.h"
 
+#include <oleacc.h>
+
 struct NEWEST_IA2_INTERFACE;
 
 namespace mozilla {
 
 namespace mscom {
 
 class StructToStream;