diff --git a/call/rtp_transport_controller_send.cc b/call/rtp_transport_controller_send.cc
index 9e8117f9ce..c86e667185 100644
--- a/call/rtp_transport_controller_send.cc
+++ b/call/rtp_transport_controller_send.cc
@@ -670,15 +670,18 @@ void RtpTransportControllerSend::OnReceivedRtcpReceiverReportBlocks(
 
   // Compute the packet loss from all report blocks.
   for (const RTCPReportBlock& report_block : report_blocks) {
-    auto it = last_report_blocks_.find(report_block.source_ssrc);
-    if (it != last_report_blocks_.end()) {
-      auto number_of_packets = report_block.extended_highest_sequence_number -
-                               it->second.extended_highest_sequence_number;
-      total_packets_delta += number_of_packets;
-      auto lost_delta = report_block.packets_lost - it->second.packets_lost;
-      total_packets_lost_delta += lost_delta;
+    auto [it, inserted] =
+        last_report_blocks_.try_emplace(report_block.source_ssrc);
+    LossReport& last_loss_report = it->second;
+    if (!inserted) {
+      total_packets_delta += report_block.extended_highest_sequence_number -
+                             last_loss_report.extended_highest_sequence_number;
+      total_packets_lost_delta +=
+          report_block.packets_lost - last_loss_report.cumulative_lost;
     }
-    last_report_blocks_[report_block.source_ssrc] = report_block;
+    last_loss_report.extended_highest_sequence_number =
+        report_block.extended_highest_sequence_number;
+    last_loss_report.cumulative_lost = report_block.packets_lost;
   }
   // Can only compute delta if there has been previous blocks to compare to. If
   // not, total_packets_delta will be unchanged and there's nothing more to do.
diff --git a/call/rtp_transport_controller_send.h b/call/rtp_transport_controller_send.h
index b5134a523e..4d6f6e68a9 100644
--- a/call/rtp_transport_controller_send.h
+++ b/call/rtp_transport_controller_send.h
@@ -179,7 +179,11 @@ class RtpTransportControllerSend final
 
   TimeDelta process_interval_ RTC_GUARDED_BY(sequence_checker_);
 
-  std::map<uint32_t, RTCPReportBlock> last_report_blocks_
+  struct LossReport {
+    uint32_t extended_highest_sequence_number = 0;
+    int cumulative_lost = 0;
+  };
+  std::map<uint32_t, LossReport> last_report_blocks_
       RTC_GUARDED_BY(sequence_checker_);
   Timestamp last_report_block_time_ RTC_GUARDED_BY(sequence_checker_);