diff --git a/quic/core/http/quic_spdy_session.h b/quic/core/http/quic_spdy_session.h
index 1f94a79..68becb6 100644
--- a/quic/core/http/quic_spdy_session.h
+++ b/quic/core/http/quic_spdy_session.h
@@ -249,6 +249,9 @@
     return receive_control_stream_;
   }
 
+  // Initializes HTTP/3 unidirectional streams if not yet initialzed.
+  virtual void MaybeInitializeHttp3UnidirectionalStreams();
+
  private:
   friend class test::QuicSpdySessionPeer;
 
@@ -266,9 +269,6 @@
   void OnPriority(spdy::SpdyStreamId stream_id,
                   const spdy::SpdyStreamPrecedence& precedence);
 
-  // Initializes HTTP/3 unidirectional streams if not yet initialzed.
-  void MaybeInitializeHttp3UnidirectionalStreams();
-
   std::unique_ptr<QpackEncoder> qpack_encoder_;
   std::unique_ptr<QpackDecoder> qpack_decoder_;
 
diff --git a/quic/tools/quic_simple_server_session.cc b/quic/tools/quic_simple_server_session.cc
index 8f7dcf8..cf2c569 100644
--- a/quic/tools/quic_simple_server_session.cc
+++ b/quic/tools/quic_simple_server_session.cc
@@ -33,11 +33,7 @@
                             crypto_config,
                             compressed_certs_cache),
       highest_promised_stream_id_(
-          VersionHasStreamType(connection->transport_version())
-              ? QuicUtils::GetFirstUnidirectionalStreamId(
-                    connection->transport_version(),
-                    Perspective::IS_SERVER)
-              : QuicUtils::GetInvalidStreamId(connection->transport_version())),
+          QuicUtils::GetInvalidStreamId(connection->transport_version())),
       quic_simple_server_backend_(quic_simple_server_backend) {
   DCHECK(quic_simple_server_backend_);
 }
@@ -238,4 +234,14 @@
     HandlePromisedPushRequests();
   }
 }
+
+void QuicSimpleServerSession::MaybeInitializeHttp3UnidirectionalStreams() {
+  size_t previous_static_stream_count = num_outgoing_static_streams();
+  QuicSpdySession::MaybeInitializeHttp3UnidirectionalStreams();
+  size_t current_static_stream_count = num_outgoing_static_streams();
+  DCHECK_GE(current_static_stream_count, previous_static_stream_count);
+  highest_promised_stream_id_ +=
+      QuicUtils::StreamIdDelta(transport_version()) *
+      (current_static_stream_count - previous_static_stream_count);
+}
 }  // namespace quic
diff --git a/quic/tools/quic_simple_server_session.h b/quic/tools/quic_simple_server_session.h
index 12748ad..d485e7c 100644
--- a/quic/tools/quic_simple_server_session.h
+++ b/quic/tools/quic_simple_server_session.h
@@ -102,6 +102,8 @@
     return quic_simple_server_backend_;
   }
 
+  void MaybeInitializeHttp3UnidirectionalStreams() override;
+
  private:
   friend class test::QuicSimpleServerSessionPeer;