diff --git a/testutil/golden.go b/testutil/golden.go
index 66e2a6c..2f31e0b 100644
--- a/testutil/golden.go
+++ b/testutil/golden.go
@@ -22,13 +22,14 @@ func CompareFileWithFixture(t *testing.T, outputFile string, opts ...option) {
 }
 
 // CompareWithFixture will compare output with a test fixture and allows to automatically update them
-// by setting the UPDATE env var.
+// by setting the UPDATE env var (configurable via WithUpdateEnv, defaulting to "UPDATE").
 // If output is not a []byte or string, it will get serialized as yaml prior to the comparison.
 // The fixtures are stored in $PWD/testdata/prefix${testName}.yaml
 func CompareWithFixture(t *testing.T, output interface{}, opts ...option) string {
 	t.Helper()
 	options := &options{
 		Extension: ".yaml",
+		UpdateEnv: "UPDATE",
 	}
 	for _, opt := range opts {
 		opt(options)
@@ -52,7 +53,7 @@ func CompareWithFixture(t *testing.T, output interface{}, opts ...option) string
 	if err != nil {
 		t.Fatalf("failed to get absolute path to testdata file: %v", err)
 	}
-	if os.Getenv("UPDATE") != "" {
+	if os.Getenv(options.UpdateEnv) != "" {
 		if err := os.MkdirAll(filepath.Dir(golden), 0755); err != nil {
 			t.Fatalf("failed to create fixture directory: %v", err)
 		}
@@ -66,7 +67,7 @@ func CompareWithFixture(t *testing.T, output interface{}, opts ...option) string
 	}
 
 	if diff := cmp.Diff(string(expected), string(serializedOutput)); diff != "" {
-		t.Errorf("got diff between expected and actual result:\nfile: %s\ndiff:\n%s\n\nIf this is expected, re-run the test with `UPDATE=true go test ./...` to update the fixtures.", golden, diff)
+		t.Errorf("got diff between expected and actual result:\nfile: %s\ndiff:\n%s\n\nIf this is expected, re-run the test with `%s=1 go test ./...` to update the fixtures.", golden, diff, options.UpdateEnv)
 	}
 
 	return golden
@@ -77,7 +78,8 @@ type options struct {
 	Suffix    string
 	Extension string
 
-	SubDir string
+	SubDir    string
+	UpdateEnv string
 }
 
 type option func(*options)
@@ -100,6 +102,12 @@ func WithSubDir(subDir string) option {
 	}
 }
 
+func WithUpdateEnv(env string) option {
+	return func(opts *options) {
+		opts.UpdateEnv = env
+	}
+}
+
 // golden determines the golden file to use
 func golden(t *testing.T, opts *options) (string, error) {
 	if opts.Extension == "" {