diff --git a/src/pkg/syscall/syscall_windows.go b/src/pkg/syscall/syscall_windows.go
index 33a86ce251e..06dde518fdc 100644
--- a/src/pkg/syscall/syscall_windows.go
+++ b/src/pkg/syscall/syscall_windows.go
@@ -708,6 +708,7 @@ const (
 	PTRACE_TRACEME = 1 + iota
 	WNOHANG
 	WSTOPPED
+	WUNTRACED
 	SYS_CLOSE
 	SYS_WRITE
 	SYS_EXIT