diff --git a/Aaru.Filesystems/CBM/CBM.cs b/Aaru.Filesystems/CBM/CBM.cs
index 7224ee55b..62ea60123 100644
--- a/Aaru.Filesystems/CBM/CBM.cs
+++ b/Aaru.Filesystems/CBM/CBM.cs
@@ -43,6 +43,7 @@ public sealed partial class CBM : IReadOnlyFilesystem
     Dictionary<string, CachedFile> _cache;
     bool                           _debug;
     byte[]                         _diskHeader;
+    bool                           _is1581;
     bool                           _mounted;
     byte[]                         _root;
     FileSystemInfo                 _statfs;
@@ -95,4 +96,15 @@ public sealed partial class CBM : IReadOnlyFilesystem
             "debug", false.ToString()
         }
     };
+
+    ulong CbmChsToLba(byte track, byte sector, bool is1581)
+    {
+        if(track == 0 || track > 40)
+            return 0;
+
+        if(is1581)
+            return (ulong)((track - 1) * 40 + sector - 1);
+
+        return trackStartingLbas[track - 1] + sector;
+    }
 }
\ No newline at end of file
diff --git a/Aaru.Filesystems/CBM/Consts.cs b/Aaru.Filesystems/CBM/Consts.cs
index 14239a8c3..30bc86f0f 100644
--- a/Aaru.Filesystems/CBM/Consts.cs
+++ b/Aaru.Filesystems/CBM/Consts.cs
@@ -33,4 +33,10 @@ namespace Aaru.Filesystems;
 public sealed partial class CBM
 {
     const string FS_TYPE = "cbmfs";
+
+    readonly ulong[] trackStartingLbas =
+    [
+        0, 21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231, 252, 273, 294, 315, 336, 357, 376, 395, 414, 433, 452,
+        471, 490, 508, 526, 544, 562, 580, 598, 615, 632, 649, 666, 683, 700, 717, 734, 751
+    ];
 }
\ No newline at end of file
diff --git a/Aaru.Filesystems/CBM/Super.cs b/Aaru.Filesystems/CBM/Super.cs
index 674debd5f..352a7bb34 100644
--- a/Aaru.Filesystems/CBM/Super.cs
+++ b/Aaru.Filesystems/CBM/Super.cs
@@ -115,10 +115,11 @@ public sealed partial class CBM
             if(cbmHdr.directoryTrack == 0)
                 return ErrorNumber.InvalidArgument;
 
-            rootLba               = (ulong)((cbmHdr.directoryTrack - 1) * 40 + cbmHdr.directorySector - 1);
+            rootLba               = CbmChsToLba(cbmHdr.directoryTrack, cbmHdr.directorySector, true);
             serial                = cbmHdr.diskId;
             Metadata.VolumeName   = StringHandlers.CToString(cbmHdr.name, encoding);
             Metadata.VolumeSerial = $"{cbmHdr.diskId}";
+            _is1581               = true;
         }
         else
         {
@@ -133,7 +134,7 @@ public sealed partial class CBM
                           and { unused1   : 0x00, directoryTrack: 0x12 }))
                 return ErrorNumber.InvalidArgument;
 
-            rootLba = (ulong)((cbmBam.directoryTrack - 1) * 40 + cbmBam.directorySector - 1);
+            rootLba = CbmChsToLba(cbmBam.directoryTrack, cbmBam.directorySector, false);
             serial  = cbmBam.diskId;
 
             Metadata.VolumeName   = StringHandlers.CToString(cbmBam.name, encoding);
@@ -159,7 +160,7 @@ public sealed partial class CBM
             if(sector[0] == 0)
                 break;
 
-            nextLba = (ulong)((sector[0] - 1) * 40 + sector[1] - 1);
+            nextLba = CbmChsToLba(sector[0], sector[1], _is1581);
         } while(nextLba > 0);
 
         _root = rootMs.ToArray();
@@ -254,7 +255,7 @@ public sealed partial class CBM
 
             var data = new MemoryStream();
 
-            nextLba = (ulong)((dirEntry.firstFileBlockTrack - 1) * 40 + dirEntry.firstFileBlockSector - 1);
+            nextLba = CbmChsToLba(dirEntry.firstFileBlockTrack, dirEntry.firstFileBlockSector, _is1581);
 
             _statfs.FreeBlocks -= (ulong)dirEntry.blocks;
 
@@ -272,7 +273,7 @@ public sealed partial class CBM
                 if(sector[0] == 0)
                     break;
 
-                nextLba = (ulong)((sector[0] - 1) * 40 + sector[1] - 1);
+                nextLba = CbmChsToLba(sector[0], sector[1], _is1581);
             }
 
             FileAttributes attributes = FileAttributes.File;