diff --git a/winpr/include/winpr/pool.h b/winpr/include/winpr/pool.h
index d4af20b83..2c707ad09 100644
--- a/winpr/include/winpr/pool.h
+++ b/winpr/include/winpr/pool.h
@@ -128,11 +128,18 @@ typedef VOID (*PTP_WORK_CALLBACK)(PTP_CALLBACK_INSTANCE Instance, PVOID Context,
 typedef VOID (*PTP_TIMER_CALLBACK)(PTP_CALLBACK_INSTANCE Instance, PVOID Context, PTP_TIMER Timer);
 typedef VOID (*PTP_WAIT_CALLBACK)(PTP_CALLBACK_INSTANCE Instance, PVOID Context, PTP_WAIT Wait, TP_WAIT_RESULT WaitResult);
 
+#endif
+
+
+/* Non-Windows and pre Vista */
+#if ((!defined(_WIN32)) || (defined(_WIN32) && (_WIN32_WINNT < 0x0600)))
+
 typedef VOID (*PTP_WIN32_IO_CALLBACK)(PTP_CALLBACK_INSTANCE Instance, PVOID Context, PVOID Overlapped,
-		ULONG IoResult, ULONG_PTR NumberOfBytesTransferred, PTP_IO Io);
+	ULONG IoResult, ULONG_PTR NumberOfBytesTransferred, PTP_IO Io);
 
 #endif
 
+
 /* Synch */
 
 WINPR_API PTP_WAIT CreateThreadpoolWait(PTP_WAIT_CALLBACK pfnwa, PVOID pv, PTP_CALLBACK_ENVIRON pcbe);