diff --git a/index.d.ts b/index.d.ts
index 432fe0de..ed696e90 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -93,6 +93,8 @@ export class AggregatorRegistry extends Registry {
 	 * Gets aggregated metrics for all workers. The optional callback and
 	 * returned Promise resolve with the same value; either may be used.
 	 * @param {Function?} cb (err, metrics) => any
+	 * @param {Object?} opt options for
+	 * @param {Registry?} opt.registry additional registry to merge with
 	 * @return {Promise<string>} Promise that resolves with the aggregated
 	 *   metrics.
 	 */
diff --git a/lib/cluster.js b/lib/cluster.js
index 89f5c20c..c33ea250 100644
--- a/lib/cluster.js
+++ b/lib/cluster.js
@@ -17,6 +17,7 @@ const GET_METRICS_REQ = 'prom-client:getMetricsReq';
 const GET_METRICS_RES = 'prom-client:getMetricsRes';
 
 let registries = [Registry.globalRegistry];
+let additionRegistry;
 let requestCtr = 0; // Concurrency control
 let listenersAdded = false;
 const requests = new Map(); // Pending requests for workers' local metrics.
@@ -31,12 +32,16 @@ class AggregatorRegistry extends Registry {
 	 * Gets aggregated metrics for all workers. The optional callback and
 	 * returned Promise resolve with the same value; either may be used.
 	 * @param {Function?} callback (err, metrics) => any
+	 * @param {Object} opt options for
+	 * @param {Registry} opt.registry additional registry to merge with
 	 * @return {Promise<string>} Promise that resolves with the aggregated
 	 *   metrics.
 	 */
-	clusterMetrics(callback) {
+	clusterMetrics(callback, opt) {
 		const requestId = requestCtr++;
-
+		if (opt && opt.registry) {
+			additionRegistry = opt.registry;
+		}
 		return new Promise((resolve, reject) => {
 			function done(err, result) {
 				// Don't resolve/reject the promise if a callback is provided
@@ -96,6 +101,11 @@ class AggregatorRegistry extends Registry {
 		const aggregatedRegistry = new Registry();
 		const metricsByName = new Grouper();
 
+		// add addition registry such as master
+		if (additionRegistry) {
+			metricsArr.push(additionRegistry.getMetricsAsJSON());
+		}
+
 		// Gather by name
 		metricsArr.forEach(metrics => {
 			metrics.forEach(metric => {
diff --git a/package-lock.json b/package-lock.json
index f5446f74..2923e41f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
 	"name": "prom-client",
-	"version": "11.5.2",
+	"version": "11.5.3",
 	"lockfileVersion": 1,
 	"requires": true,
 	"dependencies": {