diff --git a/decode_int.go b/decode_int.go
index 07e6276..6a50e4d 100644
--- a/decode_int.go
+++ b/decode_int.go
@@ -38,26 +38,42 @@ func (d *intDecoder) parseInt(b []byte) int64 {
 	return sum
 }
 
+var (
+	numTable = [256]bool{
+		'0': true,
+		'1': true,
+		'2': true,
+		'3': true,
+		'4': true,
+		'5': true,
+		'6': true,
+		'7': true,
+		'8': true,
+		'9': true,
+	}
+)
+
 func (d *intDecoder) decodeByte(buf []byte, cursor int) ([]byte, int, error) {
-	buflen := len(buf)
-	for ; cursor < buflen; cursor++ {
+	for {
 		switch buf[cursor] {
 		case ' ', '\n', '\t', '\r':
+			cursor++
 			continue
 		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
 			start := cursor
 			cursor++
-			for ; cursor < buflen; cursor++ {
-				tk := int(buf[cursor])
-				if int('0') <= tk && tk <= int('9') {
-					continue
-				}
-				break
+		LOOP:
+			if numTable[buf[cursor]] {
+				cursor++
+				goto LOOP
 			}
 			num := buf[start:cursor]
 			return num, cursor, nil
+		default:
+			goto ERROR
 		}
 	}
+ERROR:
 	return nil, 0, errors.New("unexpected error number")
 }
 
diff --git a/decode_string.go b/decode_string.go
index d2d4a9e..701e00e 100644
--- a/decode_string.go
+++ b/decode_string.go
@@ -25,8 +25,6 @@ func (d *stringDecoder) decode(buf []byte, cursor int, p uintptr) (int, error) {
 func (d *stringDecoder) decodeByte(buf []byte, cursor int) ([]byte, int, error) {
 	for {
 		switch buf[cursor] {
-		case '\000':
-			return nil, 0, errors.New("unexpected error key delimiter")
 		case ' ', '\n', '\t', '\r':
 			cursor++
 		case '"':
@@ -62,7 +60,10 @@ func (d *stringDecoder) decodeByte(buf []byte, cursor int) ([]byte, int, error)
 			}
 			cursor += 5
 			return []byte{'n', 'u', 'l', 'l'}, cursor, nil
+		default:
+			goto ERROR
 		}
 	}
+ERROR:
 	return nil, 0, errors.New("unexpected error key delimiter")
 }