diff --git a/build.go b/build.go
index 57ea53f..f96439f 100644
--- a/build.go
+++ b/build.go
@@ -36,7 +36,7 @@ func NewBuilder(signer Signer) *Builder {
 			Type:      "JWT",
 		},
 	}
-	b.headerRaw = encodeHeader(&b.header)
+	b.headerRaw = encodeHeader(b.header)
 	return b
 }
 
@@ -77,7 +77,6 @@ func (b *Builder) Build(claims interface{}) (*Token, error) {
 	raw[idx] = '.'
 	idx++
 	base64Encode(raw[idx:], signature)
-	idx += lenS
 
 	token := &Token{
 		raw:       raw,
@@ -98,43 +97,12 @@ func encodeClaims(claims interface{}) ([]byte, error) {
 	}
 }
 
-func encodeHeader(header *Header) []byte {
+func encodeHeader(header Header) []byte {
 	if header.Type == "JWT" && header.ContentType == "" {
-		switch header.Algorithm {
-		case EdDSA:
-			return []byte(encHeaderEdDSA)
-
-		case HS256:
-			return []byte(encHeaderHS256)
-		case HS384:
-			return []byte(encHeaderHS384)
-		case HS512:
-			return []byte(encHeaderHS512)
-
-		case RS256:
-			return []byte(encHeaderRS256)
-		case RS384:
-			return []byte(encHeaderRS384)
-		case RS512:
-			return []byte(encHeaderRS512)
-
-		case ES256:
-			return []byte(encHeaderES256)
-		case ES384:
-			return []byte(encHeaderES384)
-		case ES512:
-			return []byte(encHeaderES512)
-
-		case PS256:
-			return []byte(encHeaderPS256)
-		case PS384:
-			return []byte(encHeaderPS384)
-		case PS512:
-			return []byte(encHeaderPS512)
-
-		default:
-			// another algorithm? encode below
+		if h := getPredefinedHeader(header); h != nil {
+			return h
 		}
+		// another algorithm? encode below
 	}
 	// returned err is always nil, see *Header.MarshalJSON
 	buf, _ := json.Marshal(header)
@@ -144,6 +112,44 @@ func encodeHeader(header *Header) []byte {
 	return encoded
 }
 
+func getPredefinedHeader(header Header) []byte {
+	switch header.Algorithm {
+	case EdDSA:
+		return []byte(encHeaderEdDSA)
+
+	case HS256:
+		return []byte(encHeaderHS256)
+	case HS384:
+		return []byte(encHeaderHS384)
+	case HS512:
+		return []byte(encHeaderHS512)
+
+	case RS256:
+		return []byte(encHeaderRS256)
+	case RS384:
+		return []byte(encHeaderRS384)
+	case RS512:
+		return []byte(encHeaderRS512)
+
+	case ES256:
+		return []byte(encHeaderES256)
+	case ES384:
+		return []byte(encHeaderES384)
+	case ES512:
+		return []byte(encHeaderES512)
+
+	case PS256:
+		return []byte(encHeaderPS256)
+	case PS384:
+		return []byte(encHeaderPS384)
+	case PS512:
+		return []byte(encHeaderPS512)
+
+	default:
+		return nil
+	}
+}
+
 const (
 	encHeaderEdDSA = "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9"
 
diff --git a/example_test.go b/example_test.go
index 627ea7c..16d6cc1 100644
--- a/example_test.go
+++ b/example_test.go
@@ -27,7 +27,8 @@ func Example_JWT() {
 	builder := jwt.NewBuilder(signer)
 
 	// 4. and build a token
-	token, err := builder.Build(claims)
+	token, errBuild := builder.Build(claims)
+	checkErr(errBuild)
 
 	// 5. here is your token  :)
 	var _ []byte = token.Raw() // or just token.String() for string