diff --git a/2017/state-of-go-may/alias/main.go b/2017/state-of-go-may/alias/main.go
index ddc386e..9e93c99 100644
--- a/2017/state-of-go-may/alias/main.go
+++ b/2017/state-of-go-may/alias/main.go
@@ -1,3 +1,5 @@
+// +build go1.9
+
 package main
 
 import (
diff --git a/2017/state-of-go-may/bits/main.go b/2017/state-of-go-may/bits/main.go
index ad3ca08..e791883 100644
--- a/2017/state-of-go-may/bits/main.go
+++ b/2017/state-of-go-may/bits/main.go
@@ -1,3 +1,5 @@
+// +build go1.9
+
 package main
 
 import (
diff --git a/2017/state-of-go-may/syncmap/main.go b/2017/state-of-go-may/syncmap/main.go
index aeccb68..c389c62 100644
--- a/2017/state-of-go-may/syncmap/main.go
+++ b/2017/state-of-go-may/syncmap/main.go
@@ -1,3 +1,5 @@
+// +build go1.9
+
 package main
 
 import (