diff --git a/reactos/include/ndk/rtlfuncs.h b/reactos/include/ndk/rtlfuncs.h
index a0b8a723a26..4ec355f5a67 100644
--- a/reactos/include/ndk/rtlfuncs.h
+++ b/reactos/include/ndk/rtlfuncs.h
@@ -2332,6 +2332,8 @@ RtlInitializeContext(
 );
 
 #ifdef _M_AMD64
+typedef struct _WOW64_CONTEXT *PWOW64_CONTEXT;
+
 NTSYSAPI
 NTSTATUS
 NTAPI