diff --git a/internal/testutil/env.go b/internal/testutil/env.go
deleted file mode 100644
index f2427f5..0000000
--- a/internal/testutil/env.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package testutil
-
-import (
-	"os"
-	"testing"
-)
-
-// Based on https://github.com/frankban/quicktest/blob/577841610793d24f99e31cc2c0ef3a541fefd7c7/patch.go#L34-L64
-// Licensed under the MIT license
-// Copyright (c) 2017 Canonical Ltd.
-
-// Unsetenv unsets an environment variable for the duration of a test.
-func Unsetenv(t *testing.T, name string) {
-	setenv(t, name, "", false)
-}
-
-// setenv sets or unsets an environment variable to a temporary value for the
-// duration of the test
-func setenv(t *testing.T, name, val string, valOK bool) {
-	oldVal, oldOK := os.LookupEnv(name)
-	if valOK {
-		os.Setenv(name, val)
-	} else {
-		os.Unsetenv(name)
-	}
-	t.Cleanup(func() {
-		if oldOK {
-			os.Setenv(name, oldVal)
-		} else {
-			os.Unsetenv(name)
-		}
-	})
-}
diff --git a/internal/testutil/env_go1_16.go b/internal/testutil/env_go1_16.go
index 5c1f7f9..8769a44 100644
--- a/internal/testutil/env_go1_16.go
+++ b/internal/testutil/env_go1_16.go
@@ -20,3 +20,21 @@ import (
 func Setenv(t *testing.T, name, val string) {
 	setenv(t, name, val, true)
 }
+
+// setenv sets or unsets an environment variable to a temporary value for the
+// duration of the test
+func setenv(t *testing.T, name, val string, valOK bool) {
+	oldVal, oldOK := os.LookupEnv(name)
+	if valOK {
+		os.Setenv(name, val)
+	} else {
+		os.Unsetenv(name)
+	}
+	t.Cleanup(func() {
+		if oldOK {
+			os.Setenv(name, oldVal)
+		} else {
+			os.Unsetenv(name)
+		}
+	})
+}