--- a/dom/media/tests/mochitest/pc.js
+++ b/dom/media/tests/mochitest/pc.js
@@ -1849,19 +1849,19 @@ PeerConnectionWrapper.prototype = {
                   info("REVERSED timestamps: rec:" +
                     rem.packetsReceived + " time:" + rem.timestamp + " sent:" + res.packetsSent + " time:" + res.timestamp);
                 }
                 // Else we may have received more than outdated Rtcp packetsSent
                 ok(rem.bytesReceived <= res.bytesSent, "No more than sent bytes");
               }
               ok(rem.jitter !== undefined, "Rtcp jitter");
               if (rem.roundTripTime) {
-                ok(rem.roundTripTime > 0,
+                ok(rem.roundTripTime >= 0,
                    "Rtcp rtt " + rem.roundTripTime + " >= 0");
-                ok(rem.roundTripTime < 60000,
+                ok(rem.roundTripTime < 60,
                    "Rtcp rtt " + rem.roundTripTime + " < 1 min");
               }
             } else {
               ok(rem.type == "remote-outbound-rtp", "Rtcp is outbound");
               ok(rem.packetsSent !== undefined, "Rtcp packetsSent");
               // We may have received more than outdated Rtcp packetsSent
               ok(rem.bytesSent >= rem.packetsSent, "Rtcp bytesSent");
             }

--- a/dom/webidl/RTCStatsReport.webidl
+++ b/dom/webidl/RTCStatsReport.webidl
@@ -52,17 +52,17 @@ dictionary RTCRtpStreamStats : RTCStats 
   double framerateStdDev;
 };
 
 dictionary RTCInboundRTPStreamStats : RTCRtpStreamStats {
   unsigned long packetsReceived;
   unsigned long long bytesReceived;
   double jitter;
   unsigned long packetsLost;
-  long roundTripTime;
+  double roundTripTime;
 
   // Video decoder measurement, not present in RTCP case
   unsigned long discardedPackets;
   unsigned long framesDecoded;
 };
 
 
 dictionary RTCOutboundRTPStreamStats : RTCRtpStreamStats {

--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionCtx.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionCtx.cpp
@@ -234,17 +234,17 @@ void PeerConnectionCtx::DeliverStats(RTC
                        : WEBRTC_VIDEO_QUALITY_INBOUND_JITTER;
         }
         Accumulate(id, s.mJitter.Value());
       }
       if (s.mRoundTripTime.WasPassed()) {
         MOZ_ASSERT(isRemote);
         HistogramID id = isAudio ? WEBRTC_AUDIO_QUALITY_OUTBOUND_RTT
                                  : WEBRTC_VIDEO_QUALITY_OUTBOUND_RTT;
-        Accumulate(id, s.mRoundTripTime.Value());
+        Accumulate(id, s.mRoundTripTime.Value() * 1000);
       }
       if (lastReport && lastReport->mInboundRTPStreamStats.WasPassed() &&
           s.mBytesReceived.WasPassed()) {
         auto& laststats = lastReport->mInboundRTPStreamStats.Value();
         auto i = FindId(laststats, s.mId.Value());
         if (i != laststats.NoIndex) {
           auto& lasts = laststats[i];
           if (lasts.mBytesReceived.WasPassed()) {

--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp
@@ -2837,18 +2837,18 @@ RefPtr<RTCStatsQueryPromise> PeerConnect
             s.mMediaType.Construct(
                 kind);  // mediaType is the old name for kind.
             s.mKind.Construct(kind);
             s.mJitter.Construct(double(jitterMs) / 1000);
             s.mLocalId.Construct(localId);
             s.mPacketsReceived.Construct(packetsReceived);
             s.mBytesReceived.Construct(bytesReceived);
             s.mPacketsLost.Construct(packetsLost);
-            if (rtt > 0) {
-              s.mRoundTripTime.Construct(rtt);
+            if (rtt > 0) { // RTT is not reported when it is zero
+              s.mRoundTripTime.Construct(static_cast<double>(rtt) / 1000);
             }
             query->report->mInboundRTPStreamStats.Value().AppendElement(
                 s, fallible);
           }
         }
         // Then, fill in local side (with cross-link to remote only if present)
         {
           RTCOutboundRTPStreamStats s;

--- a/toolkit/content/aboutwebrtc/aboutWebrtc.js
+++ b/toolkit/content/aboutwebrtc/aboutWebrtc.js
@@ -559,17 +559,17 @@ RTPStats.prototype = {
 
       if (stats.bytesReceived) {
         statsString += ` (${(stats.bytesReceived / 1024).toFixed(2)} Kb)`;
       }
 
       statsString += ` ${getString("lost_label")}: ${stats.packetsLost} ${getString("jitter_label")}: ${stats.jitter}`;
 
       if (stats.roundTripTime) {
-        statsString += ` RTT: ${stats.roundTripTime} ms`;
+        statsString += ` RTT: ${stats.roundTripTime * 1000} ms`;
       }
     } else if (stats.packetsSent) {
       statsString += ` ${getString("sent_label")}: ${stats.packetsSent} ${getString("packets")}`;
       if (stats.bytesSent) {
         statsString += ` (${(stats.bytesSent / 1024).toFixed(2)} Kb)`;
       }
     }