diff --git a/src/win32/thread.cpp b/src/win32/thread.cpp
index 000ab8779..55986b9b2 100644
--- a/src/win32/thread.cpp
+++ b/src/win32/thread.cpp
@@ -577,7 +577,7 @@ namespace boost
                 } Reason;
             } REASON_CONTEXT, *PREASON_CONTEXT;
             typedef BOOL (WINAPI *setwaitabletimerex_t)(HANDLE, const LARGE_INTEGER *, LONG, PTIMERAPCROUTINE, LPVOID, PREASON_CONTEXT, ULONG);
-            static inline BOOL WINAPI SetWaitableTimerEx_emulation(HANDLE hTimer, const LARGE_INTEGER *lpDueTime, LONG lPeriod, PTIMERAPCROUTINE pfnCompletionRoutine, LPVOID lpArgToCompletionRoutine, PREASON_CONTEXT WakeContext, ULONG TolerableDelay)
+            static inline BOOL WINAPI SetWaitableTimerEx_emulation(HANDLE hTimer, const LARGE_INTEGER *lpDueTime, LONG lPeriod, PTIMERAPCROUTINE pfnCompletionRoutine, LPVOID lpArgToCompletionRoutine, PREASON_CONTEXT, ULONG)
             {
                 return SetWaitableTimer(hTimer, lpDueTime, lPeriod, pfnCompletionRoutine, lpArgToCompletionRoutine, FALSE);
             }