diff --git a/dll/win32/vssapi/main.c b/dll/win32/vssapi/main.c
index 427447c2a15..acb24003397 100644
--- a/dll/win32/vssapi/main.c
+++ b/dll/win32/vssapi/main.c
@@ -16,48 +16,24 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
+#ifndef __REACTOS__
 #include "config.h"
+#endif
 #include <stdarg.h>
 #include "windef.h"
 #include "winbase.h"
 #include "vss.h"
 #include "vswriter.h"
+#include "wine/asm.h"
 #include "wine/debug.h"
 
-WINE_DEFAULT_DEBUG_CHANNEL( vssapi );
-
-#ifdef __i386__  /* thiscall functions are i386-specific */
-
-#define THISCALL(func) __thiscall_ ## func
-#define THISCALL_NAME(func) __ASM_NAME("__thiscall_" #func)
-#undef __thiscall
-#define __thiscall __stdcall
+#ifdef __REACTOS__
 #ifdef _MSC_VER
-#define DEFINE_THISCALL_WRAPPER(func,args) \
-    void __declspec(naked) __thiscall_ ##func(void) \
-    { \
-        __asm { pop eax } \
-        __asm { push ecx } \
-        __asm { push eax } \
-        __asm { jmp func } \
-    }
-#else
-#define DEFINE_THISCALL_WRAPPER(func,args) \
-    extern void THISCALL(func)(void); \
-    __ASM_GLOBAL_FUNC(__thiscall_ ## func, \
-                      "popl %eax\n\t" \
-                      "pushl %ecx\n\t" \
-                      "pushl %eax\n\t" \
-                      "jmp " __ASM_NAME(#func) __ASM_STDCALL(args) )
+#define __thiscall __stdcall
+#endif
 #endif
-#else /* __i386__ */
 
-#define THISCALL(func) func
-#define THISCALL_NAME(func) __ASM_NAME(#func)
-#define __thiscall __cdecl
-#define DEFINE_THISCALL_WRAPPER(func,args) /* nothing */
-
-#endif /* __i386__ */
+WINE_DEFAULT_DEBUG_CHANNEL( vssapi );
 
 struct CVssWriter
 {
diff --git a/dll/win32/vssapi/vssapi.spec b/dll/win32/vssapi/vssapi.spec
index 84f9003ddc5..3c6ec60e356 100644
--- a/dll/win32/vssapi/vssapi.spec
+++ b/dll/win32/vssapi/vssapi.spec
@@ -2,9 +2,9 @@
 @ stub VssFreeSnapshotProperties
 @ stub ShouldBlockRevert
 @ stub ??0CVssJetWriter@@QAE@XZ
-@ cdecl -arch=i386 ??0CVssWriter@@QAE@XZ(ptr) __thiscall_VSSAPI_CVssWriter_default_ctor
+@ cdecl -arch=i386 ??0CVssWriter@@QAE@XZ(ptr) VSSAPI_CVssWriter_default_ctor
 @ stub ??1CVssJetWriter@@UAE@XZ
-@ cdecl -arch=i386 ??1CVssWriter@@UAE@XZ(ptr) __thiscall_VSSAPI_CVssWriter_dtor
+@ cdecl -arch=i386 ??1CVssWriter@@UAE@XZ(ptr) VSSAPI_CVssWriter_dtor
 @ stub ?AreComponentsSelected@CVssJetWriter@@IBG_NXZ
 @ stub ?AreComponentsSelected@CVssWriter@@IBG_NXZ
 @ stub ?CreateVssBackupComponents@@YGJPAPAVIVssBackupComponents@@@Z
@@ -27,7 +27,7 @@
 @ stub ?GetSnapshotDeviceName@CVssJetWriter@@IBGJPBGPAPBG@Z
 @ stub ?GetSnapshotDeviceName@CVssWriter@@IBGJPBGPAPBG@Z
 @ stub ?Initialize@CVssJetWriter@@QAGJU_GUID@@PBG_N211K@Z
-@ cdecl -arch=i386 ?Initialize@CVssWriter@@QAGJU_GUID@@PBGW4VSS_USAGE_TYPE@@W4VSS_SOURCE_TYPE@@W4_VSS_APPLICATION_LEVEL@@KW4VSS_ALTERNATE_WRITER_STATE@@_N@Z(ptr ptr wstr long long long long long long wstr) __thiscall_VSSAPI_CVssWriter_Initialize
+@ cdecl -arch=i386 ?Initialize@CVssWriter@@QAGJU_GUID@@PBGW4VSS_USAGE_TYPE@@W4VSS_SOURCE_TYPE@@W4_VSS_APPLICATION_LEVEL@@KW4VSS_ALTERNATE_WRITER_STATE@@_N@Z(ptr ptr wstr long long long long long long wstr) VSSAPI_CVssWriter_Initialize
 @ stub ?InstallAlternateWriter@CVssWriter@@QAGJU_GUID@@0@Z
 @ stub ?IsBootableSystemStateBackedUp@CVssJetWriter@@IBG_NXZ
 @ stub ?IsBootableSystemStateBackedUp@CVssWriter@@IBG_NXZ
@@ -67,9 +67,9 @@
 @ stub ?OnVSSShutdown@CVssWriter@@UAG_NXZ
 @ stub ?SetWriterFailure@CVssJetWriter@@IAGJJ@Z
 @ stub ?SetWriterFailure@CVssWriter@@IAGJJ@Z
-@ cdecl -arch=i386 ?Subscribe@CVssWriter@@QAGJK@Z(ptr long) __thiscall_VSSAPI_CVssWriter_Subscribe
+@ cdecl -arch=i386 ?Subscribe@CVssWriter@@QAGJK@Z(ptr long) VSSAPI_CVssWriter_Subscribe
 @ stub ?Uninitialize@CVssJetWriter@@QAGXXZ
-@ cdecl -arch=i386 ?Unsubscribe@CVssWriter@@QAGJXZ(ptr) __thiscall_VSSAPI_CVssWriter_Unsubscribe
+@ cdecl -arch=i386 ?Unsubscribe@CVssWriter@@QAGJXZ(ptr) VSSAPI_CVssWriter_Unsubscribe
 @ stub CreateVssBackupComponentsInternal
 @ stub CreateVssExamineWriterMetadataInternal
 @ stub CreateVssExpressWriterInternal
diff --git a/media/doc/README.WINE b/media/doc/README.WINE
index 050a8fe31c8..2d72bc86a44 100644
--- a/media/doc/README.WINE
+++ b/media/doc/README.WINE
@@ -194,7 +194,7 @@ dll/win32/usp10               # Synced to WineStaging-4.18
 dll/win32/uxtheme             # Forked
 dll/win32/vbscript            # Synced to WineStaging-4.18
 dll/win32/version             # Synced to WineStaging-4.18
-dll/win32/vssapi              # Synced to WineStaging-2.9
+dll/win32/vssapi              # Synced to WineStaging-4.18
 dll/win32/wbemdisp            # Synced to WineStaging-4.0
 dll/win32/wbemprox            # Synced to WineStaging-4.0
 dll/win32/windowscodecs       # Synced to WineStaging-4.0