diff --git a/dsa_test.go b/dsa_test.go
index dc6c7f0..fd7296c 100644
--- a/dsa_test.go
+++ b/dsa_test.go
@@ -230,7 +230,10 @@ func TestDSASignatures(t *testing.T) {
 func testDsaFixture(f *dsaFixture, t *testing.T) {
 	t.Logf("Testing %s", f.name)
 
-	digest := f.alg.digest([]byte(f.message))
+	h := f.alg()
+	h.Write([]byte(f.message))
+	digest := h.Sum(nil)
+
 	g := f.key.subgroup / 8
 	if len(digest) > g {
 		digest = digest[0:g]
diff --git a/ecdsa_test.go b/ecdsa_test.go
index 30daa5d..cc244e7 100644
--- a/ecdsa_test.go
+++ b/ecdsa_test.go
@@ -416,7 +416,10 @@ func ecdsaLoadInt(s string) (n *big.Int) {
 func testEcsaFixture(f *ecdsaFixture, t *testing.T) {
 	t.Logf("Testing %s", f.name)
 
-	digest := f.alg.digest([]byte(f.message))
+	h := f.alg()
+	h.Write([]byte(f.message))
+	digest := h.Sum(nil)
+
 	g := f.key.subgroup / 8
 	if len(digest) > g {
 		digest = digest[0:g]
diff --git a/rfc6979.go b/rfc6979.go
index 41cb1dd..b3d5941 100644
--- a/rfc6979.go
+++ b/rfc6979.go
@@ -27,13 +27,6 @@ import (
 // A function which provides a fresh Hash (e.g., sha256.New).
 type HashAlgorithm func() hash.Hash
 
-// digest returns a digest of the given message.
-func (alg HashAlgorithm) digest(m []byte) []byte {
-	h := alg()
-	h.Write(m)
-	return h.Sum(nil)
-}
-
 // mac returns an HMAC of the given key and message.
 func (alg HashAlgorithm) mac(k []byte, m []byte) []byte {
 	h := hmac.New(alg, k)