diff --git a/vrclient_x64/cxx.h b/vrclient_x64/cxx.h
index 701ab02f..373af218 100644
--- a/vrclient_x64/cxx.h
+++ b/vrclient_x64/cxx.h
@@ -16,6 +16,8 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
+#ifndef __WINE_CXX_H
+#define __WINE_CXX_H
 #include "wine/asm.h"
 
 #ifdef _WIN64
@@ -474,3 +476,5 @@ __ASM_BLOCK_BEGIN(type_info_vtables) \
     __ASM_VTABLE(type_info, \
             VTABLE_ADD_FUNC(type_info_vector_dtor)); \
 __ASM_BLOCK_END
+
+#endif
diff --git a/vrclient_x64/flatapi.h b/vrclient_x64/flatapi.h
index faf14132..c53d4447 100644
--- a/vrclient_x64/flatapi.h
+++ b/vrclient_x64/flatapi.h
@@ -1,6 +1,8 @@
 /* asm thunks for the flat (FnTable) API */
 
 #ifdef __i386__
+
+#include "cxx.h"
 #include "pshpack1.h"
 struct thunk
 {
@@ -24,7 +26,11 @@ static inline void init_thunk( struct thunk *thunk, void *this, void *proc,
   thunk->mov_edx = 0xba;
   thunk->proc = proc;
   thunk->jmp = 0xe9;
+#ifdef __ASM_USE_THISCALL_WRAPPER
   thunk->call_flat = (char *)call_flat_method - (char *)(&thunk->call_flat + 1);
+#else
+  thunk->call_flat = (char *)proc - (char *)(&thunk->call_flat + 1);
+#endif
 }
 
 #else