diff --git a/README.md b/README.md
index e6cff60..d2aaf78 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 Stats for Hypercores, with Prometheus support.
 
+Assumes the hypercores are replicated over UDX streams. This is the case for all normal use-cases of hypercores (like replicating across hyperdht/hyperswarm).
+
 ## Install
 
 ```
diff --git a/index.js b/index.js
index cbd8abf..81adc39 100644
--- a/index.js
+++ b/index.js
@@ -53,6 +53,10 @@ class HypercoreStats {
     return this._getStats().totalMaxInflightBlocks
   }
 
+  getAvgRoundTripTimeMs () {
+    return this._getStats().avgRoundTripTimeMs
+  }
+
   // getTotalBlocksUploaded () {
   //   return this._getStats().totalBlocksUploaded
   // }
@@ -190,6 +194,13 @@ class HypercoreStats {
       }
     })
 
+    new promClient.Gauge({ // eslint-disable-line no-new
+      name: 'hypercore_round_trip_time_avg_seconds',
+      help: 'Average round-trip time (rtt) for the open replication streams',
+      collect () {
+        this.set(self.getAvgRoundTripTimeMs() / 1000)
+      }
+    })
     /*
     new promClient.Gauge({ // eslint-disable-line no-new
       name: 'hypercore_total_blocks_uploaded',
@@ -386,6 +397,7 @@ class HypercoreStatsSnapshot {
     this.totalLength = 0
     this.totalInflightBlocks = 0
     this.totalMaxInflightBlocks = 0
+    this._totalRoundTripTime = 0
     // this.totalBlocksUploaded = 0
     // this.totalBlocksDownloaded = 0
     // this.totalBytesUploaded = 0
@@ -398,6 +410,12 @@ class HypercoreStatsSnapshot {
     return this._totalPeersConns.size
   }
 
+  get avgRoundTripTimeMs () {
+    return this.totalPeers === 0
+      ? 0
+      : this._totalRoundTripTime / this.totalPeers
+  }
+
   calculate () {
     this.totalCores = this.cores.length
 
@@ -428,9 +446,11 @@ class HypercoreStatsSnapshot {
       }
 
       for (const peer of core.peers) {
+        const udxStream = peer.stream.rawStream
         this.totalInflightBlocks += peer.inflight
-        this._totalPeersConns.add(peer.stream.rawStream)
+        this._totalPeersConns.add(udxStream)
         this.totalMaxInflightBlocks += peer.getMaxInflight()
+        this._totalRoundTripTime += udxStream.rtt
       }
     }
   }
diff --git a/package.json b/package.json
index 4167b67..2b0543b 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,8 @@
     "brittle": "^3.6.1",
     "corestore": "^6.18.4",
     "hypercore": "^10.37.19",
+    "hyperdht": "^6.16.5",
+    "hyperswarm": "^4.8.2",
     "prom-client": "^15.1.3",
     "random-access-memory": "^6.2.1",
     "standard": "^17.1.0"
diff --git a/test.js b/test.js
index bd91b43..11eb525 100644
--- a/test.js
+++ b/test.js
@@ -3,6 +3,8 @@ const Corestore = require('corestore')
 const RAM = require('random-access-memory')
 const HypercoreStats = require('.')
 const promClient = require('prom-client')
+const setupTestnet = require('hyperdht/testnet')
+const Hyperswarm = require('hyperswarm')
 
 const DEBUG = false
 
@@ -33,6 +35,7 @@ test('Can register and get prometheus metrics', async (t) => {
     t.is(getMetricValue(lines, 'hypercore_total_inflight_blocks'), 0, 'hypercore_total_inflight_blocks init 0')
     t.is(getMetricValue(lines, 'hypercore_total_max_inflight_blocks'), 0, 'hypercore_total_max_inflight_blocks init 0')
     t.is(getMetricValue(lines, 'hypercore_total_peers'), 0, 'hypercore_total_peers init 0')
+    t.is(getMetricValue(lines, 'hypercore_round_trip_time_avg_seconds'), 0, 'hypercore_round_trip_time_avg_seconds init 0')
 
     // t.is(getMetricValue(lines, 'hypercore_total_blocks_downloaded'), 0, 'hypercore_total_blocks_downloaded init 0')
     // t.is(getMetricValue(lines, 'hypercore_total_blocks_uploaded'), 0, 'hypercore_total_blocks_uploaded init 0')
@@ -65,10 +68,24 @@ test('Can register and get prometheus metrics', async (t) => {
   const readCore = store2.get({ key: core.key })
   await readCore.ready()
 
-  // Add error handlers if it turns out these can error
-  const s1 = core.replicate(true)
-  const s2 = readCore.replicate(false)
-  s1.pipe(s2).pipe(s1)
+  // Some stats come from udx, so we need UDX streams
+  // instead of directly replicating the hypercores.
+  // Easiest to just use hyperswarm for that.
+  const testnet = await setupTestnet()
+  const bootstrap = testnet.bootstrap
+  const swarm1 = new Hyperswarm({ bootstrap })
+  swarm1.on('connection', (conn) => {
+    store.replicate(conn)
+  })
+  const swarm2 = new Hyperswarm({ bootstrap })
+  swarm2.on('connection', (conn) => {
+    store2.replicate(conn)
+  })
+
+  swarm1.join(core.discoveryKey)
+  await swarm1.flush()
+  swarm2.join(core.discoveryKey)
+  await new Promise(resolve => setImmediate(resolve))
 
   await readCore.get(0)
   // DEVNOTE: The precise lifecycle of when a peer is added to
@@ -88,6 +105,7 @@ test('Can register and get prometheus metrics', async (t) => {
     // TODO: proper test of inflight metrics
     t.is(getMetricValue(lines, 'hypercore_total_length'), 3, 'hypercore_total_length')
     t.is(getMetricValue(lines, 'hypercore_total_peers'), 1, 'hypercore_total_peers')
+    t.is(getMetricValue(lines, 'hypercore_round_trip_time_avg_seconds') > 0, true, 'hypercore_round_trip_time_avg_seconds')
     // t.is(getMetricValue(lines, 'hypercore_total_blocks_downloaded'), 0, 'hypercore_total_blocks_downloaded')
     // t.is(getMetricValue(lines, 'hypercore_total_blocks_uploaded'), 1, 'hypercore_total_blocks_uploaded')
     // t.is(getMetricValue(lines, 'hypercore_total_bytes_downloaded'), 0, 'hypercore_total_bytes_downloaded')
@@ -99,6 +117,10 @@ test('Can register and get prometheus metrics', async (t) => {
     t.ok(getMetricValue(lines, 'hypercore_total_wire_request_received') > 0, 'hypercore_total_wire_request_received')
     t.ok(getMetricValue(lines, 'hypercore_total_wire_range_transmitted') > 0, 'hypercore_total_wire_range_transmitted')
   }
+
+  await swarm1.destroy()
+  await swarm2.destroy()
+  await testnet.destroy()
 })
 
 test('Cache-expiry logic', async (t) => {
@@ -116,7 +138,7 @@ test('Cache-expiry logic', async (t) => {
     const metrics = await promClient.register.metrics()
 
     const lines = metrics.split('\n')
-    if (DEBUG) console.log(metrics)
+    // if (DEBUG) console.log(metrics)
     t.is(getMetricValue(lines, 'hypercore_total_cores'), 0, 'init 0 (sanity check)')
   }
 
@@ -154,7 +176,7 @@ function getMetricValue (lines, name) {
   const match = lines.find((l) => l.startsWith(`${name} `))
   if (!match) throw new Error(`No match for ${name}`)
 
-  const value = parseInt(match.split(' ')[1])
+  const value = parseFloat(match.split(' ')[1])
   if (DEBUG) console.log(name, '->', value)
 
   return value