diff --git a/BinaryDad.Coding/Hubs/CodeHub.cs b/BinaryDad.Coding/Hubs/CodeHub.cs
index 800601b..03b4c18 100644
--- a/BinaryDad.Coding/Hubs/CodeHub.cs
+++ b/BinaryDad.Coding/Hubs/CodeHub.cs
@@ -10,11 +10,17 @@ namespace BinaryDad.Coding.Hubs
         {
             if (index == 0)
             {
-                Users.Sessions[Context.ConnectionId].Html = code;
+                if (Users.Sessions.TryGetValue(Context.ConnectionId, out User value))
+                {
+                    value.Html = code;
+                }
             }
             else if (index == 1)
             {
-                Users.Sessions[Context.ConnectionId].Css = code;
+                if (Users.Sessions.TryGetValue(Context.ConnectionId, out User value))
+                {
+                    value.Css = code;
+                }
             }
 
             // only send to all if it's a teacher
@@ -28,9 +34,12 @@ namespace BinaryDad.Coding.Hubs
 
         public async Task SaveName(string name, string color)
         {
-            Users.Sessions[Context.ConnectionId].Id = Context.ConnectionId;
-            Users.Sessions[Context.ConnectionId].Name = name;
-            Users.Sessions[Context.ConnectionId].Color = string.IsNullOrWhiteSpace(color) ? "white" : color;
+            if (!Users.Sessions.ContainsKey(Context.ConnectionId))
+            {
+                Users.Sessions[Context.ConnectionId].Id = Context.ConnectionId;
+                Users.Sessions[Context.ConnectionId].Name = name;
+                Users.Sessions[Context.ConnectionId].Color = string.IsNullOrWhiteSpace(color) ? "white" : color;
+            }
 
             await Clients.All.SendAsync("UsersList", Users.Sessions);
         }
@@ -49,7 +58,10 @@ namespace BinaryDad.Coding.Hubs
 
         public override async Task OnDisconnectedAsync(Exception exception)
         {
-            Users.Sessions.Remove(Context.ConnectionId);
+            if (Users.Sessions.ContainsKey(Context.ConnectionId))
+            {
+                Users.Sessions.Remove(Context.ConnectionId);
+            }
 
             await Clients.All.SendAsync("UsersList", Users.Sessions);