diff --git a/evp.go b/evp.go
index 1fd08fd..b595ce9 100644
--- a/evp.go
+++ b/evp.go
@@ -168,7 +168,7 @@ func loadHash(ch crypto.Hash) *hashAlgorithm {
 			hash.md = md
 		}
 	}
-	hash.marshallable = isHashMarshallable(hash.md)
+	hash.marshallable = hash.magic != "" && isHashMarshallable(hash.md)
 	cacheMD.Store(ch, &hash)
 	return &hash
 }
diff --git a/hash.go b/hash.go
index a40c2bc..d01dd68 100644
--- a/hash.go
+++ b/hash.go
@@ -384,7 +384,7 @@ func (d *evpHash) AppendBinary(buf []byte) ([]byte, error) {
 	case crypto.SHA512:
 		appender = (*sha512State)(state)
 	default:
-		return nil, errors.New("openssl: unsupported hash function: " + strconv.Itoa(int(d.alg.ch)))
+		panic("openssl: unsupported hash function: " + strconv.Itoa(int(d.alg.ch)))
 	}
 	buf = append(buf, d.alg.magic[:]...)
 	return appender.AppendBinary(buf)
@@ -422,7 +422,7 @@ func (d *evpHash) UnmarshalBinary(b []byte) error {
 	case crypto.SHA512:
 		unmarshaler = (*sha512State)(state)
 	default:
-		return errors.New("openssl: unsupported hash function: " + strconv.Itoa(int(d.alg.ch)))
+		panic("openssl: unsupported hash function: " + strconv.Itoa(int(d.alg.ch)))
 	}
 	return unmarshaler.UnmarshalBinary(b)
 }
diff --git a/hash_test.go b/hash_test.go
index 12b00c3..948be94 100644
--- a/hash_test.go
+++ b/hash_test.go
@@ -110,7 +110,7 @@ func TestHash_BinaryMarshaler(t *testing.T) {
 
 			state, err := hashMarshaler.MarshalBinary()
 			if err != nil {
-				if strings.Contains(err.Error(), "unsupported hash function") {
+				if strings.Contains(err.Error(), "hash state is not marshallable") {
 					t.Skip("BinaryMarshaler not supported")
 				}
 				t.Fatalf("MarshalBinary failed: %v", err)
@@ -160,7 +160,7 @@ func TestHash_BinaryAppender(t *testing.T) {
 			// Append binary data to the prebuilt slice
 			state, err := hashWithBinaryAppender.AppendBinary(prebuiltSlice)
 			if err != nil {
-				if strings.Contains(err.Error(), "unsupported hash function") {
+				if strings.Contains(err.Error(), "hash state is not marshallable") {
 					t.Skip("AppendBinary not supported")
 				}
 				t.Errorf("could not append binary: %v", err)