diff --git a/src/filo-fs-ext2.ads b/src/filo-fs-ext2.ads
index ba47aef..a13b153 100644
--- a/src/filo-fs-ext2.ads
+++ b/src/filo-fs-ext2.ads
@@ -48,9 +48,10 @@
    subtype Block_Size is Natural range 2 ** Log_Block_Size'First .. 2 ** Log_Block_Size'Last;
    subtype Max_Block_Index is Index_Type range 0 .. 2 ** Log_Block_Size'Last - 1;
 
-   -- Minimum ext2 block size is 1KiB (two 512B blocks)
-   type FSBlock_Offset is new Block_Offset range 0 .. Block_Offset'Last / 2;
-   type FSBlock_Logical is new Block_Offset range 0 .. Block_Offset'Last / 2;
+   -- Extent physical addresses are 48 bits.
+   type FSBlock_Offset is new Block_Offset range 0 .. 2 ** 48 - 1;
+   -- Logical block addresses are 32 bits.
+   type FSBlock_Logical is new Block_Offset range 0 .. 2 ** 32 - 1;
 
    -- We use a 64KiB cache which fits at least one ext2 block. If a lower
    -- block size is encountered (likely), we partition the cache into up
@@ -65,7 +66,9 @@
 
    -- Same as the 12 direct + 3 indirect blocks times 4B:
    subtype Inode_Extents_Index is Natural range 0 .. 59;
-   subtype Inode_Extents is Buffer_Type (Inode_Extents_Index);
+   subtype Inode_Extents is Buffer_Type (Inode_Extents_Index)
+   with
+      Object_Size => (Inode_Extents_Index'Last + 1) * 8;
 
    type Inode_Index is new Unsigned_32 range 2 .. Unsigned_32'Last;
    subtype Inode_Size is Positive range 128 .. Positive (Unsigned_16'Last);
@@ -79,7 +82,7 @@
       Mode        : Inode_Type := Inode_Type'First;
       Size        : Inode_Length := 0;
       Use_Extents : Boolean := False;
-      Inline      : Buffer_Type (Inode_Extents_Index) := (others => 16#00#);
+      Inline      : Inode_Extents := (others => 16#00#);
    end record;
 
    type T is record