diff --git a/plugins/serializers/carbon2/carbon2_test.go b/plugins/serializers/carbon2/carbon2_test.go
index 45a0b71140730..7ed98d6e6d6da 100644
--- a/plugins/serializers/carbon2/carbon2_test.go
+++ b/plugins/serializers/carbon2/carbon2_test.go
@@ -233,22 +233,22 @@ func TestSerializeMetricBool(t *testing.T) {
 	}{
 		{
 			metric:   requireMetric(t, now, false),
-			format:   Carbon2FormatFieldSeparate,
+			format:   string(Carbon2FormatFieldSeparate),
 			expected: fmt.Sprintf("metric=cpu field=java_lang_GarbageCollector_Valid tag_name=tag_value  0 %d\n", now.Unix()),
 		},
 		{
 			metric:   requireMetric(t, now, false),
-			format:   Carbon2FormatMetricIncludesField,
+			format:   string(Carbon2FormatMetricIncludesField),
 			expected: fmt.Sprintf("metric=cpu_java_lang_GarbageCollector_Valid tag_name=tag_value  0 %d\n", now.Unix()),
 		},
 		{
 			metric:   requireMetric(t, now, true),
-			format:   Carbon2FormatFieldSeparate,
+			format:   string(Carbon2FormatFieldSeparate),
 			expected: fmt.Sprintf("metric=cpu field=java_lang_GarbageCollector_Valid tag_name=tag_value  1 %d\n", now.Unix()),
 		},
 		{
 			metric:   requireMetric(t, now, true),
-			format:   Carbon2FormatMetricIncludesField,
+			format:   string(Carbon2FormatMetricIncludesField),
 			expected: fmt.Sprintf("metric=cpu_java_lang_GarbageCollector_Valid tag_name=tag_value  1 %d\n", now.Unix()),
 		},
 	}