diff --git a/lib/formatter.js b/lib/formatter.js
index 982d9383..f4e5a9db 100644
--- a/lib/formatter.js
+++ b/lib/formatter.js
@@ -30,22 +30,33 @@ function getFormatter(metric, defaultLabels) {
 }
 
 function getLabelsCode(metric, defaultLabelNames, defaultLabels) {
-	let labelString = '';
+	const labelString = [];
 	const labelNames = getLabelNames(metric, defaultLabelNames);
 	for (let index = 0; index < labelNames.length; index++) {
+		const comma = index > 0 ? ',' : '';
 		const labelName = labelNames[index];
 		if (labelName === 'quantile') {
-			labelString += `\${val.labels.quantile != null ? \`quantile="\${escapeLabelValue(val.labels.quantile)}"\` : ''}`;
+			labelString.push(
+				`\${val.labels.quantile != null ? \`${comma}quantile="\${escapeLabelValue(val.labels.quantile)}"\` : ''}`,
+			);
 		} else if (labelName === 'le') {
-			labelString += `\${val.labels.le != null ? \`le="\${escapeLabelValue(val.labels.le)}"\` : ''}`;
+			labelString.push(
+				`\${val.labels.le != null ? \`${comma}le="\${escapeLabelValue(val.labels.le)}"\` : ''}`,
+			);
 		} else {
-			labelString += `${labelName}="\${val.labels['${labelName}'] ? escapeLabelValue(val.labels['${labelName}']) : escapeLabelValue('${defaultLabels[labelName]}')}"`;
-		}
-		if (index !== labelNames.length - 1 && labelString.length > 0) {
-			labelString += ',';
+			const defaultLabelValue = defaultLabels[labelName];
+			if (typeof defaultLabelValue === 'undefined') {
+				labelString.push(
+					`\${val.labels['${labelName}'] != null ? \`${comma}${labelName}="\${escapeLabelValue(val.labels['${labelName}'])}"\` : ''}`,
+				);
+			} else {
+				labelString.push(
+					`${comma}${labelName}="\${escapeLabelValue(val.labels['${labelName}']  || '${defaultLabelValue}')}"`,
+				);
+			}
 		}
 	}
-	return labelString;
+	return labelString.join('');
 }
 
 function getLabelNames(metric, defaultLabelNames) {
diff --git a/test/registerTest.js b/test/registerTest.js
index 370b7305..1ecc63a2 100644
--- a/test/registerTest.js
+++ b/test/registerTest.js
@@ -103,6 +103,32 @@ describe('register', () => {
 		expect(output).toEqual('test_metric{testLabel="testValue"} 1');
 	});
 
+	it('should handle a metric with default labels with value 0', () => {
+		register.setDefaultLabels({ testLabel: 0 });
+		const counter = new Counter({
+			name: 'test_metric',
+			help: 'A test metric',
+		});
+		counter.inc(1);
+		register.registerMetric(counter);
+
+		const output = register.metrics().split('\n')[2];
+		expect(output).toEqual('test_metric{testLabel="0"} 1');
+	});
+
+	it('should handle a metrics with labels subset', () => {
+		const gauge = new Gauge({
+			name: 'test_metric',
+			help: 'help',
+			labelNames: ['code', 'success'],
+		});
+		gauge.inc({ code: '200' }, 10);
+		register.registerMetric(gauge);
+
+		const output = register.metrics().split('\n')[2];
+		expect(output).toEqual('test_metric{code="200"} 10');
+	});
+
 	it('labeled metrics should take precidence over defaulted', () => {
 		register.setDefaultLabels({ testLabel: 'testValue' });
 		const counter = new Counter({