diff --git a/pc/peerconnection_integrationtest.cc b/pc/peerconnection_integrationtest.cc
index 1e61604019..7de0ad6af5 100644
--- a/pc/peerconnection_integrationtest.cc
+++ b/pc/peerconnection_integrationtest.cc
@@ -2581,6 +2581,27 @@ TEST_P(PeerConnectionIntegrationTest,
   ASSERT_TRUE(inbound_stream_stats[0]->track_id.is_defined());
 }
 
+// Same as above but for the legacy stats implementation.
+TEST_P(PeerConnectionIntegrationTest,
+       GetStatsForUnsignaledStreamWithOldStatsApi) {
+  ASSERT_TRUE(CreatePeerConnectionWrappers());
+  ConnectFakeSignaling();
+  caller()->AddAudioTrack();
+  // Remove SSRCs and MSIDs from the received offer SDP.
+  callee()->SetReceivedSdpMunger(RemoveSsrcsAndMsids);
+  caller()->CreateAndSetAndSignalOffer();
+  ASSERT_TRUE_WAIT(SignalingStateStable(), kDefaultTimeout);
+
+  // Note that, since the old stats implementation associates SSRCs with tracks
+  // using SDP, when SSRCs aren't signaled in SDP these stats won't have an
+  // associated track ID. So we can't use the track "selector" argument.
+  //
+  // Also, we use "EXPECT_TRUE_WAIT" because the stats collector may decide to
+  // return cached stats if not enough time has passed since the last update.
+  EXPECT_TRUE_WAIT(callee()->OldGetStats()->BytesReceived() > 0U,
+                   kDefaultTimeout);
+}
+
 // Test that we can successfully get the media related stats (audio level
 // etc.) for the unsignaled stream.
 TEST_P(PeerConnectionIntegrationTest,
diff --git a/pc/statscollector.cc b/pc/statscollector.cc
index fc001894d3..6c5cdab014 100644
--- a/pc/statscollector.cc
+++ b/pc/statscollector.cc
@@ -554,6 +554,9 @@ void StatsCollector::UpdateStats(
   const double kMinGatherStatsPeriod = 50;
   if (stats_gathering_started_ != 0 &&
       stats_gathering_started_ + kMinGatherStatsPeriod > time_now) {
+    RTC_LOG(LS_INFO)
+        << "Not updating stats again, since they were updated within "
+        << kMinGatherStatsPeriod << "ms.";
     return;
   }
   stats_gathering_started_ = time_now;
@@ -586,18 +589,15 @@ StatsReport* StatsCollector::PrepareReport(bool local,
   // Use the ID of the track that is currently mapped to the SSRC, if any.
   std::string track_id;
   if (!GetTrackIdBySsrc(ssrc, &track_id, direction)) {
-    if (!report) {
-      // The ssrc is not used by any track or existing report, return NULL
-      // in such case to indicate no report is prepared for the ssrc.
-      return NULL;
+    // The SSRC is not used by any existing track (or lookup failed since the
+    // SSRC wasn't signaled in SDP). Try copying the track ID from a previous
+    // report: if one exists.
+    if (report) {
+      const StatsReport::Value* v =
+          report->FindValue(StatsReport::kStatsValueNameTrackId);
+      if (v)
+        track_id = v->string_val();
     }
-
-    // The ssrc is not used by any existing track. Keeps the old track id
-    // since we want to report the stats for inactive ssrc.
-    const StatsReport::Value* v =
-        report->FindValue(StatsReport::kStatsValueNameTrackId);
-    if (v)
-      track_id = v->string_val();
   }
 
   if (!report)
@@ -607,7 +607,9 @@ StatsReport* StatsCollector::PrepareReport(bool local,
   report->set_timestamp(stats_gathering_started_);
 
   report->AddInt64(StatsReport::kStatsValueNameSsrc, ssrc);
-  report->AddString(StatsReport::kStatsValueNameTrackId, track_id);
+  if (!track_id.empty()) {
+    report->AddString(StatsReport::kStatsValueNameTrackId, track_id);
+  }
   // Add the mapping of SSRC to transport.
   report->AddId(StatsReport::kStatsValueNameTransportId, transport_id);
   return report;