diff --git a/algorithm_test.go b/algorithm_test.go
index 060819e..a10b45d 100644
--- a/algorithm_test.go
+++ b/algorithm_test.go
@@ -19,8 +19,6 @@ import (
 	"bytes"
 	"crypto"
 	"crypto/rand"
-	_ "crypto/sha256"
-	_ "crypto/sha512"
 	"flag"
 	"fmt"
 	"strings"
diff --git a/digestset/set_test.go b/digestset/set_test.go
index 7a01c24..d2c5174 100644
--- a/digestset/set_test.go
+++ b/digestset/set_test.go
@@ -17,7 +17,6 @@ package digestset
 
 import (
 	"crypto/sha256"
-	_ "crypto/sha512"
 	"encoding/binary"
 	"math/rand"
 	"testing"
diff --git a/sha.go b/sha.go
index 0e2201f..a9f864f 100644
--- a/sha.go
+++ b/sha.go
@@ -2,6 +2,12 @@ package digest
 
 import (
 	"crypto"
+
+	// make sure crypto.SHA256 is registered
+	_ "crypto/sha256"
+
+	// make sure crypto.sha512 and crypto.SHA384 are registered
+	_ "crypto/sha512"
 )
 
 const (