diff --git a/winpr/include/winpr/pool.h b/winpr/include/winpr/pool.h
index c2d3aff6e..1b4656358 100644
--- a/winpr/include/winpr/pool.h
+++ b/winpr/include/winpr/pool.h
@@ -127,6 +127,11 @@ typedef TP_CALLBACK_ENVIRON_V1 TP_CALLBACK_ENVIRON, *PTP_CALLBACK_ENVIRON;
 typedef VOID (*PTP_WORK_CALLBACK)(PTP_CALLBACK_INSTANCE Instance, PVOID Context, PTP_WORK Work);
 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
+
+#if !(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);