diff --git a/src/filo-fs-iso9660.ads b/src/filo-fs-iso9660.ads
index 480ce39..20d2989 100644
--- a/src/filo-fs-iso9660.ads
+++ b/src/filo-fs-iso9660.ads
@@ -23,7 +23,7 @@
       In_Root     : in     Boolean;
       Success     : out    Boolean)
    with
-      Pre => Is_Mounted (State),
+      Pre => Is_Mounted (State) and File_Name'Length <= Natural'Last - 3,
       Post => (if Success then Is_Open (State) else Is_Mounted (State));
 
    procedure Close (State : in out T)
@@ -73,24 +73,28 @@
    -- We'll use the absolute position of the dir record
    subtype Inode_Index is FS_Record
    with
-      Dynamic_Predicate => Inode_Index.Offset <= Directory_Record_Offset'Last;
+      Dynamic_Predicate =>
+         Inode_Index.Size >= Directory_Record'Length;
    type Inode_Length is range 0 .. FSBlock_Count'Last * FSBlock_Size;
 
    type Mount_State is record
       Part_Len    : Partition_Length := 0;
-      Root_Inode  : Inode_Index := (others => <>);
+      Root_Inode  : Inode_Index := (Size => Directory_Record'Length, others => <>);
    end record;
 
    type Extent is record
       Start : FSBlock := 0;
       Count : FSBlock_Count := 0;
-   end record;
+   end record
+   with
+      Dynamic_Predicate =>
+         Start <= FSBlock_Count'Last - Count;
 
    type Extent_Range is range 0 .. 0; -- Linux allows 100 "file sections"
    type Extents is array (Extent_Range) of Extent;
 
    type Inode_Info is record
-      I        : Inode_Index := (others => <>);
+      I        : Inode_Index := (Size => Directory_Record'Length, others => <>);
       Mode     : File_Type := File_Type'First;
       Size     : Inode_Length := 0;
       Extents  : ISO9660.Extents := (Extent_Range => (others => <>));
@@ -100,7 +104,7 @@
       Static   : Mount_State  := (others => <>);
       S        : State;
       Inode    : Inode_Info := (others => <>);
-      Cur_Dir  : Inode_Index := (others => <>);
+      Cur_Dir  : Inode_Index := (Size => Directory_Record'Length, others => <>);
    end record;
 
 end FILO.FS.ISO9660;