diff --git a/v3/pkg/w32/timer.go b/v3/pkg/w32/timer.go
index 7f49f07fa..c95253e53 100644
--- a/v3/pkg/w32/timer.go
+++ b/v3/pkg/w32/timer.go
@@ -1,3 +1,5 @@
+//go:build windows
+
 package w32
 
 func SetTimer(hwnd HWND, nIDEvent uintptr, uElapse uint32, lpTimerFunc uintptr) uintptr {
@@ -14,4 +16,4 @@ func KillTimer(hwnd HWND, nIDEvent uintptr) bool {
 		uintptr(hwnd),
 		nIDEvent)
 	return ret != 0
-}
\ No newline at end of file
+}