diff --git a/README.md b/README.md
index 0659326..89aa3b5 100644
--- a/README.md
+++ b/README.md
@@ -53,6 +53,7 @@ Which labels to include in `http_request_duration_seconds` metric:
 * **metricsPath**: replace the `/metrics` route with a **regex** or exact **string**. Note: it is highly recommended to just stick to the default
 * **metricType**: histogram/summary selection. See more details below
 
+
 ### metricType option ###
 
 Two metric types are supported for `http_request_duration_seconds` metric:
@@ -85,6 +86,7 @@ Additional options for **summary**:
 * **promClient**: options for promClient startup, e.g. **collectDefaultMetrics**. This option was added
   to keep `express-prom-bundle` runnable using confit (e.g. with kraken.js) without writing any JS code,
   see [advanced example](https://github.com/jochen-schweizer/express-prom-bundle/blob/master/advanced-example.js)
+* **promRegistry**: Optional `promClient.Registry` instance to attach metrics to. Defaults to global `promClient.register`.
 
 ### More details on includePath option
 
diff --git a/package-lock.json b/package-lock.json
index b5e66bf..5361f5b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "express-prom-bundle",
-  "version": "5.1.4",
+  "version": "5.1.5",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/src/index.js b/src/index.js
index 9da8924..bf747fc 100644
--- a/src/index.js
+++ b/src/index.js
@@ -50,7 +50,8 @@ function main(opts) {
       normalizePath: main.normalizePath,
       formatStatusCode: main.normalizeStatusCode,
       metricType: 'histogram',
-      promClient: {}
+      promClient: {},
+      promRegistry: promClient.register
     }, opts
   );
 
@@ -92,14 +93,16 @@ function main(opts) {
         labelNames: labels,
         percentiles: opts.percentiles || [0.5, 0.75, 0.95, 0.98, 0.99, 0.999],
         maxAgeSeconds:  opts.maxAgeSeconds,
-        ageBuckets: opts.ageBuckets
+        ageBuckets: opts.ageBuckets,
+        registers: [opts.promRegistry]
       });
     } else if (opts.metricType === 'histogram' || !opts.metricType) {
       return new promClient.Histogram({
         name: httpMetricName,
         help: 'duration histogram of http responses labeled with: ' + labels.join(', '),
         labelNames: labels,
-        buckets: opts.buckets || [0.003, 0.03, 0.1, 0.3, 1.5, 10]
+        buckets: opts.buckets || [0.003, 0.03, 0.1, 0.3, 1.5, 10],
+        registers: [opts.promRegistry]
       });
     } else {
       throw new Error('metricType option must be histogram or summary');
@@ -113,14 +116,15 @@ function main(opts) {
   if (opts.includeUp !== false) {
     metrics.up = new promClient.Gauge({
       name: 'up',
-      help: '1 = up, 0 = not up'
+      help: '1 = up, 0 = not up',
+      registers: [opts.promRegistry]
     });
     metrics.up.set(1);
   }
 
   const metricsMiddleware = function(req, res) {
     res.writeHead(200, {'Content-Type': 'text/plain'});
-    res.end(promClient.register.metrics());
+    res.end(opts.promRegistry.metrics());
   };
 
   const metricsMatch = opts.metricsPath instanceof RegExp ? opts.metricsPath
diff --git a/types/index.d.ts b/types/index.d.ts
index 1a77877..d5645c4 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -1,7 +1,7 @@
 // TypeScript Version: 2.8
 
 import { Request, RequestHandler, Response } from 'express';
-import { DefaultMetricsCollectorConfiguration } from 'prom-client';
+import { DefaultMetricsCollectorConfiguration, Registry } from 'prom-client';
 
 export {};
 
@@ -31,6 +31,7 @@ declare namespace express_prom_bundle {
     metricType?: 'summary' | 'histogram';
     metricsPath?: string;
     promClient?: { collectDefaultMetrics?: DefaultMetricsCollectorConfiguration };
+    promRegistry?: Registry,
     normalizePath?: NormalizePathEntry[] | NormalizePathFn;
     formatStatusCode?: NormalizeStatusCodeFn;
     transformLabels?: TransformLabelsFn;
diff --git a/types/test.ts b/types/test.ts
index 354be4b..c002c43 100644
--- a/types/test.ts
+++ b/types/test.ts
@@ -47,6 +47,7 @@ promBundle({
       timeout: 1000
     }
   },
+  promRegistry: new promClient.Registry(),
   urlValueParser: {
     minHexLength: 5,
     extraMasks: [