diff --git a/Source/Core/Controls/ThingBrowserControl.cs b/Source/Core/Controls/ThingBrowserControl.cs
index 848b0b8..61101f5 100644
--- a/Source/Core/Controls/ThingBrowserControl.cs
+++ b/Source/Core/Controls/ThingBrowserControl.cs
@@ -359,9 +359,9 @@ namespace CodeImp.DoomBuilder.Controls
 							// Select this
 							if(n.TreeView != null) //mxd. Tree node may've been removed during filtering
 							{
-								n.Parent.Expand();
-								typelist.SelectedNodes.Add(n);
-								n.EnsureVisible();
+                                if (n.Parent != null) n.Parent.Expand(); // node won't have parent when the list is prefiltered
+                                typelist.SelectedNodes.Add(n);
+                                n.EnsureVisible();
 								break;
 							}
 						}
diff --git a/Source/Core/Resources/SkySphere.md3 b/Source/Core/Resources/SkySphere.md3
index b0ad8cf..536069d 100644
Binary files a/Source/Core/Resources/SkySphere.md3 and b/Source/Core/Resources/SkySphere.md3 differ
diff --git a/Source/Core/ZDoom/ZDTextParser.cs b/Source/Core/ZDoom/ZDTextParser.cs
index 8bf9105..4077fc5 100644
--- a/Source/Core/ZDoom/ZDTextParser.cs
+++ b/Source/Core/ZDoom/ZDTextParser.cs
@@ -485,6 +485,9 @@ namespace CodeImp.DoomBuilder.ZDoom
         protected void SkipStructure() { SkipStructure(new HashSet<string>()); }
         protected void SkipStructure(HashSet<string> breakat)
         {
+            // We need it to be case-insensitive
+            if (breakat.Count > 0) breakat = new HashSet<string>(breakat, StringComparer.OrdinalIgnoreCase);
+
             string token;
             do
             {