diff --git a/Barotrauma/BarotraumaClient/Source/Networking/GameClient.cs b/Barotrauma/BarotraumaClient/Source/Networking/GameClient.cs
index fbb360aea..4f3694e04 100644
--- a/Barotrauma/BarotraumaClient/Source/Networking/GameClient.cs
+++ b/Barotrauma/BarotraumaClient/Source/Networking/GameClient.cs
@@ -552,7 +552,7 @@ namespace Barotrauma.Networking
                             case ServerPacketHeader.ENDGAME:
                                 string endMessage = inc.ReadString();
                                 bool missionSuccessful = inc.ReadBoolean();
-                                if (missionSuccessful && GameMain.GameSession.Mission != null)
+                                if (missionSuccessful && GameMain.GameSession?.Mission != null)
                                 {
                                     GameMain.GameSession.Mission.Completed = true;
                                 }