diff --git a/net/dcsctp/socket/dcsctp_socket.cc b/net/dcsctp/socket/dcsctp_socket.cc
index d197a38386..48b6edb67f 100644
--- a/net/dcsctp/socket/dcsctp_socket.cc
+++ b/net/dcsctp/socket/dcsctp_socket.cc
@@ -1021,12 +1021,6 @@ void DcSctpSocket::OnSentPacket(rtc::ArrayView<const uint8_t> packet,
       DebugPrintOutgoing(packet);
     }
 
-    // The heartbeat interval timer is restarted for every sent packet, to
-    // fire when the outgoing channel is inactive.
-    if (tcb_ != nullptr) {
-      tcb_->heartbeat_handler().RestartTimer();
-    }
-
     ++metrics_.tx_packets_count;
   }
 }
diff --git a/net/dcsctp/socket/dcsctp_socket_test.cc b/net/dcsctp/socket/dcsctp_socket_test.cc
index 2d392d62f1..d27b260753 100644
--- a/net/dcsctp/socket/dcsctp_socket_test.cc
+++ b/net/dcsctp/socket/dcsctp_socket_test.cc
@@ -910,6 +910,37 @@ TEST_P(DcSctpSocketParametrizedTest, ExpectHeartbeatToBeSent) {
   MaybeHandoverSocketAndSendMessage(a, std::move(z));
 }
 
+TEST(DcSctpSocketParametrizedTest, BothSidesSendHeartbeats) {
+  // On an idle connection, both sides send heartbeats, and both sides acks.
+
+  // Make them have slightly different heartbeat intervals, to validate that
+  // sending an ack by Z doesn't restart its heartbeat timer.
+  DcSctpOptions options_a = {.heartbeat_interval = DurationMs(1000)};
+  SocketUnderTest a("A", options_a);
+
+  DcSctpOptions options_z = {.heartbeat_interval = DurationMs(1100)};
+  SocketUnderTest z("Z", options_z);
+
+  ConnectSockets(a, z);
+
+  AdvanceTime(a, z, TimeDelta::Millis(1000));
+
+  std::vector<uint8_t> packet_a = a.cb.ConsumeSentPacket();
+  EXPECT_THAT(packet_a, HasChunks(ElementsAre(IsHeartbeatRequest(_))));
+  // Z receives heartbeat, sends ACK.
+  z.socket.ReceivePacket(packet_a);
+  a.socket.ReceivePacket(z.cb.ConsumeSentPacket());
+
+  // A little while later, Z should send heartbeats to A.
+  AdvanceTime(a, z, TimeDelta::Millis(100));
+
+  std::vector<uint8_t> packet_z = z.cb.ConsumeSentPacket();
+  EXPECT_THAT(packet_z, HasChunks(ElementsAre(IsHeartbeatRequest(_))));
+  // A receives heartbeat, sends ACK.
+  a.socket.ReceivePacket(packet_z);
+  z.socket.ReceivePacket(a.cb.ConsumeSentPacket());
+}
+
 TEST_P(DcSctpSocketParametrizedTest,
        CloseConnectionAfterTooManyLostHeartbeats) {
   SocketUnderTest a("A");
diff --git a/net/dcsctp/socket/transmission_control_block.cc b/net/dcsctp/socket/transmission_control_block.cc
index 34223411cb..e179a8e4ae 100644
--- a/net/dcsctp/socket/transmission_control_block.cc
+++ b/net/dcsctp/socket/transmission_control_block.cc
@@ -244,6 +244,13 @@ void TransmissionControlBlock::SendBufferedPackets(SctpPacket::Builder& builder,
 
     auto chunks =
         retransmission_queue_.GetChunksToSend(now, builder.bytes_remaining());
+
+    if (!chunks.empty()) {
+      // https://datatracker.ietf.org/doc/html/rfc9260#section-8.3
+      // Sending DATA means that the path is not idle - restart heartbeat timer.
+      heartbeat_handler_.RestartTimer();
+    }
+
     for (auto& [tsn, data] : chunks) {
       if (capabilities_.message_interleaving) {
         builder.Add(IDataChunk(tsn, std::move(data), false));