diff --git a/internal/toml-test/json.go b/internal/toml-test/json.go
index a5fa2830..4394f419 100644
--- a/internal/toml-test/json.go
+++ b/internal/toml-test/json.go
@@ -1,3 +1,6 @@
+//go:build go1.16
+// +build go1.16
+
 package tomltest
 
 import (
diff --git a/internal/toml-test/runner.go b/internal/toml-test/runner.go
index 410df235..c0054c84 100644
--- a/internal/toml-test/runner.go
+++ b/internal/toml-test/runner.go
@@ -1,4 +1,6 @@
 //go:generate ./gen-multi.py
+//go:build go1.16
+// +build go1.16
 
 package tomltest
 
diff --git a/internal/toml-test/toml.go b/internal/toml-test/toml.go
index 346f0a96..934e6314 100644
--- a/internal/toml-test/toml.go
+++ b/internal/toml-test/toml.go
@@ -1,3 +1,6 @@
+//go:build go1.16
+// +build go1.16
+
 package tomltest
 
 import (