diff --git a/kyaml/fn/runtime/container/container.go b/kyaml/fn/runtime/container/container.go
index 590232d11..806d36702 100644
--- a/kyaml/fn/runtime/container/container.go
+++ b/kyaml/fn/runtime/container/container.go
@@ -204,10 +204,11 @@ func (c *Filter) getCommand() (string, []string) {
 	return "docker", a
 }
 
+var ignoreEnvKey []string = []string{"TMPDIR"}
+
 // shouldEnvIgnored returns true if the environment variable key should be ignored
 // by the container runtime.
 func shouldEnvIgnored(envKey string) bool {
-	ignoreEnvKey := []string{"TMPDIR"}
 	for _, k := range ignoreEnvKey {
 		if k == envKey {
 			return true
diff --git a/kyaml/fn/runtime/container/container_test.go b/kyaml/fn/runtime/container/container_test.go
index f7a071ad6..c5907576b 100644
--- a/kyaml/fn/runtime/container/container_test.go
+++ b/kyaml/fn/runtime/container/container_test.go
@@ -212,15 +212,14 @@ func TestFilter_ExitCode(t *testing.T) {
 }
 
 func TestIgnoreEnv(t *testing.T) {
-	ignoredEnvKey := []string{"TMPDIR"}
-	for _, key := range ignoredEnvKey {
+	for _, key := range ignoreEnvKey {
 		os.Setenv(key, "")
 	}
 
 	fltr := Filter{Image: "example.com:version"}
 	_, args := fltr.getCommand()
 	for _, arg := range args {
-		for _, key := range ignoredEnvKey {
+		for _, key := range ignoreEnvKey {
 			if arg == key {
 				t.Fatalf("%s should not be exported to container", key)
 			}