diff --git a/reader.go b/reader.go
index 225830d..55f5ab7 100644
--- a/reader.go
+++ b/reader.go
@@ -96,20 +96,20 @@ func NewReader(r io.ReaderAt) (*Reader, error) {
 				return nil, err
 			}
 		} else {
-			toRead := squash.s.IdCount
-			var curRead uint16
+			toRead := squash.s.FragCount
+			var curRead uint32
 			var tmp []fragEntry
 			var rdr *metadata.Reader
 			var offset int
 			for i := range fragOffsets {
-				curRead = uint16(math.Min(512, float64(toRead)))
+				curRead = uint32(math.Min(512, float64(toRead)))
 				tmp = make([]fragEntry, curRead)
 				rdr = metadata.NewReader(toreader.NewReader(r, int64(fragOffsets[i])), squash.d)
 				err = binary.Read(rdr, binary.LittleEndian, &tmp)
 				if err != nil {
 					return nil, err
 				}
-				offset = int(squash.s.IdCount - toRead)
+				offset = int(squash.s.FragCount - toRead)
 				for i := range tmp {
 					squash.fragEntries[offset+i] = tmp[i]
 				}
diff --git a/reader_fs.go b/reader_fs.go
index b1d1f77..088e47a 100644
--- a/reader_fs.go
+++ b/reader_fs.go
@@ -131,7 +131,7 @@ func (f FS) Glob(pattern string) (out []string, err error) {
 					Err:  err,
 				}
 			}
-			subGlob, err := sub.(FS).Glob(strings.Join(split[1:], "/"))
+			subGlob, err := sub.(fs.GlobFS).Glob(strings.Join(split[1:], "/"))
 			if err != nil {
 				if pathErr, ok := err.(*fs.PathError); ok {
 					if pathErr.Err == fs.ErrNotExist {
@@ -208,7 +208,7 @@ func (f FS) ReadDir(name string) ([]fs.DirEntry, error) {
 					Err:  err,
 				}
 			}
-			redDir, err := sub.(FS).ReadDir(strings.Join(split[1:], "/"))
+			redDir, err := sub.(fs.ReadDirFS).ReadDir(strings.Join(split[1:], "/"))
 			if err != nil {
 				if pathErr, ok := err.(*fs.PathError); ok {
 					if pathErr.Err == fs.ErrNotExist {
@@ -299,7 +299,7 @@ func (f FS) Stat(name string) (fs.FileInfo, error) {
 					Err:  err,
 				}
 			}
-			stat, err := sub.(FS).Stat(strings.Join(split[1:], "/"))
+			stat, err := sub.(fs.StatFS).Stat(strings.Join(split[1:], "/"))
 			if err != nil {
 				if pathErr, ok := err.(*fs.PathError); ok {
 					if pathErr.Err == fs.ErrNotExist {