3 files changed, 8 insertions, 7 deletions
diff --git a/plumbing/format/idxfile/decoder.go b/plumbing/format/idxfile/decoder.go
index 51a3904..9afdce3 100644
--- a/plumbing/format/idxfile/decoder.go
+++ b/plumbing/format/idxfile/decoder.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 
+	"github.com/go-git/go-git/v5/plumbing/hash"
 	"github.com/go-git/go-git/v5/utils/binary"
 )
 
@@ -19,7 +20,7 @@ var (
 
 const (
 	fanout         = 256
-	objectIDLength = 20
+	objectIDLength = hash.Size
 )
 
 // Decoder reads and decodes idx files from an input stream.
diff --git a/plumbing/format/idxfile/encoder.go b/plumbing/format/idxfile/encoder.go
index 6ac445f..7514737 100644
--- a/plumbing/format/idxfile/encoder.go
+++ b/plumbing/format/idxfile/encoder.go
@@ -1,7 +1,6 @@
 package idxfile
 
 import (
-	"crypto"
 	"io"
 
 	"github.com/go-git/go-git/v5/plumbing/hash"
@@ -16,7 +15,7 @@ type Encoder struct {
 
 // NewEncoder returns a new stream encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
-	h := hash.New(crypto.SHA1)
+	h := hash.New(hash.CryptoType)
 	mw := io.MultiWriter(w, h)
 	return &Encoder{mw, h}
 }
@@ -133,10 +132,10 @@ func (e *Encoder) encodeChecksums(idx *MemoryIndex) (int, error) {
 		return 0, err
 	}
 
-	copy(idx.IdxChecksum[:], e.hash.Sum(nil)[:20])
+	copy(idx.IdxChecksum[:], e.hash.Sum(nil)[:hash.Size])
 	if _, err := e.Write(idx.IdxChecksum[:]); err != nil {
 		return 0, err
 	}
 
-	return 40, nil
+	return hash.HexSize, nil
 }
diff --git a/plumbing/format/idxfile/idxfile.go b/plumbing/format/idxfile/idxfile.go
index 64dd8dc..9237a74 100644
--- a/plumbing/format/idxfile/idxfile.go
+++ b/plumbing/format/idxfile/idxfile.go
@@ -8,6 +8,7 @@ import (
 	encbin "encoding/binary"
 
 	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/hash"
 )
 
 const (
@@ -53,8 +54,8 @@ type MemoryIndex struct {
 	Offset32         [][]byte
 	CRC32            [][]byte
 	Offset64         []byte
-	PackfileChecksum [20]byte
-	IdxChecksum      [20]byte
+	PackfileChecksum [hash.Size]byte
+	IdxChecksum      [hash.Size]byte
 
 	offsetHash       map[int64]plumbing.Hash
 	offsetHashIsFull bool