diff --git a/Library/DiscUtils.Fat/Directory.cs b/Library/DiscUtils.Fat/Directory.cs
index 3feb3f4c..35dc9df1 100644
--- a/Library/DiscUtils.Fat/Directory.cs
+++ b/Library/DiscUtils.Fat/Directory.cs
@@ -420,9 +420,13 @@ internal void UpdateEntry(long id, DirectoryEntry entry)
     private void AddEntryRaw(long pos, DirectoryEntry entry)
     {
         _entries.Add(pos, entry);
+
         // Update the short and full name lookup tables
-        _shortFileNameToEntry.Add(entry.Name.ShortName, pos);
-        _fullFileNameToEntry.Add(entry.Name.FullName, pos);
+        if (!entry.Attributes.HasFlag(FatAttributes.VolumeId))
+        {
+            _shortFileNameToEntry.Add(entry.Name.ShortName, pos);
+            _fullFileNameToEntry.Add(entry.Name.FullName, pos);
+        }
     }
 
     private void LoadEntries()
diff --git a/Library/DiscUtils.Fat/FatFileSystemOptions.cs b/Library/DiscUtils.Fat/FatFileSystemOptions.cs
index 5117ad19..2237413e 100644
--- a/Library/DiscUtils.Fat/FatFileSystemOptions.cs
+++ b/Library/DiscUtils.Fat/FatFileSystemOptions.cs
@@ -39,7 +39,7 @@ internal FatFileSystemOptions()
 
     internal FatFileSystemOptions(FileSystemParameters parameters)
     {
-        if (parameters.FileNameEncoding is not null)
+        if (parameters?.FileNameEncoding is not null)
         {
             FileNameEncoding = parameters.FileNameEncoding;
         }