diff --git a/rtc_tools/rtc_event_log_visualizer/analyzer.cc b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
index cb270c1a96..287fbe2eb8 100644
--- a/rtc_tools/rtc_event_log_visualizer/analyzer.cc
+++ b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
@@ -1469,8 +1469,10 @@ void EventLogAnalyzer::CreateReceiveSideBweSimulationGraph(Plot* plot) {
     }
 
    private:
-    uint32_t last_bitrate_bps_;
-    bool bitrate_updated_;
+    // We don't know the start bitrate, but assume that it is the default 300
+    // kbps.
+    uint32_t last_bitrate_bps_ = 300000;
+    bool bitrate_updated_ = false;
   };
 
   std::multimap<int64_t, const RtpPacketType*> incoming_rtp;