diff --git a/webrtc/tools/network_tester/packet_sender.cc b/webrtc/tools/network_tester/packet_sender.cc
index a0629d9de8..6bd4dd075c 100644
--- a/webrtc/tools/network_tester/packet_sender.cc
+++ b/webrtc/tools/network_tester/packet_sender.cc
@@ -10,6 +10,7 @@
 
 #include "webrtc/tools/network_tester/packet_sender.h"
 
+#include <algorithm>
 #include <string>
 #include <utility>
 
@@ -24,20 +25,23 @@ namespace {
 class SendPacketTask : public rtc::QueuedTask {
  public:
   explicit SendPacketTask(PacketSender* packet_sender)
-      : packet_sender_(packet_sender) {}
+      : target_time_ms_(rtc::TimeMillis()), packet_sender_(packet_sender) {}
 
  private:
   bool Run() override {
     if (packet_sender_->IsSending()) {
       packet_sender_->SendPacket();
+      target_time_ms_ += packet_sender_->GetSendIntervalMs();
+      int64_t delay_ms = std::max(static_cast<int64_t>(0),
+                                  target_time_ms_ - rtc::TimeMillis());
       rtc::TaskQueue::Current()->PostDelayedTask(
-          std::unique_ptr<QueuedTask>(this),
-          packet_sender_->GetSendIntervalMs());
+          std::unique_ptr<QueuedTask>(this), delay_ms);
       return false;
     } else {
       return true;
     }
   }
+  int64_t target_time_ms_;
   PacketSender* const packet_sender_;
 };
 
diff --git a/webrtc/tools/network_tester/test_controller.cc b/webrtc/tools/network_tester/test_controller.cc
index 51deac7bb7..40af6437cb 100644
--- a/webrtc/tools/network_tester/test_controller.cc
+++ b/webrtc/tools/network_tester/test_controller.cc
@@ -22,8 +22,8 @@ TestController::TestController(int min_port,
       local_test_done_(false),
       remote_test_done_(false) {
   RTC_DCHECK_RUN_ON(&test_controller_thread_checker_);
-  send_data_.fill(42);
   packet_sender_checker_.Detach();
+  send_data_.fill(42);
   auto socket =
       std::unique_ptr<rtc::AsyncPacketSocket>(socket_factory_.CreateUdpSocket(
           rtc::SocketAddress(rtc::GetAnyIP(AF_INET), 0), min_port, max_port));
@@ -53,10 +53,11 @@ void TestController::SendData(const NetworkTesterPacket& packet,
   // Can be call from packet_sender or from test_controller thread.
   size_t packet_size = packet.ByteSize();
   send_data_[0] = packet_size;
+  packet_size++;
   packet.SerializeToArray(&send_data_[1], std::numeric_limits<char>::max());
   if (data_size && *data_size > packet_size)
     packet_size = *data_size;
-  udp_transport_->SendPacket(send_data_.data(), packet_size + 1,
+  udp_transport_->SendPacket(send_data_.data(), packet_size,
                              rtc::PacketOptions(), 0);
 }