diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index 2e206bfa11..a571a53645 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -468,6 +468,11 @@ PeerConnection::PeerConnection(
       tls_cert_verifier_(std::move(dependencies.tls_cert_verifier)),
       call_(std::move(call)),
       call_ptr_(call_.get()),
+      // RFC 3264: The numeric value of the session id and version in the
+      // o line MUST be representable with a "64 bit signed integer".
+      // Due to this constraint session id |session_id_| is max limited to
+      // LLONG_MAX.
+      session_id_(rtc::ToString(rtc::CreateRandomId64() & LLONG_MAX)),
       dtls_enabled_(dtls_enabled),
       data_channel_controller_(this),
       message_handler_(signaling_thread()),
@@ -560,12 +565,6 @@ RTCError PeerConnection::Initialize(
     NoteUsageEvent(UsageEvent::TURN_SERVER_ADDED);
   }
 
-  // RFC 3264: The numeric value of the session id and version in the
-  // o line MUST be representable with a "64 bit signed integer".
-  // Due to this constraint session id |session_id_| is max limited to
-  // LLONG_MAX.
-  session_id_ = rtc::ToString(rtc::CreateRandomId64() & LLONG_MAX);
-
   if (configuration.enable_rtp_data_channel) {
     // Enable creation of RTP data channels if the kEnableRtpDataChannels is
     // set. It takes precendence over the disable_sctp_data_channels
diff --git a/pc/peer_connection.h b/pc/peer_connection.h
index 58424dbac0..aa46feb4aa 100644
--- a/pc/peer_connection.h
+++ b/pc/peer_connection.h
@@ -271,7 +271,6 @@ class PeerConnection : public PeerConnectionInternal,
   rtc::Thread* worker_thread() const final { return context_->worker_thread(); }
 
   std::string session_id() const override {
-    RTC_DCHECK_RUN_ON(signaling_thread());
     return session_id_;
   }
 
@@ -670,7 +669,7 @@ class PeerConnection : public PeerConnectionInternal,
   rtc::scoped_refptr<RTCStatsCollector> stats_collector_
       RTC_GUARDED_BY(signaling_thread());
 
-  std::string session_id_ RTC_GUARDED_BY(signaling_thread());
+  const std::string session_id_;
 
   std::unique_ptr<JsepTransportController>
       transport_controller_;  // TODO(bugs.webrtc.org/9987): Accessed on both