diff --git a/src/syscall/ptrace_ios.go b/src/syscall/ptrace_ios.go
index 2f61a88a089..5209d1e0dd1 100644
--- a/src/syscall/ptrace_ios.go
+++ b/src/syscall/ptrace_ios.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ios
+// +build ios
+
 package syscall
 
 // Nosplit because it is called from forkAndExecInChild.