diff --git a/sign.go b/sign.go
index ba20f4d..d78a86f 100644
--- a/sign.go
+++ b/sign.go
@@ -17,8 +17,6 @@ func CheckSign(appID, appKey, random, sign string, ts int, data interface{}) boo
 		return false
 	}
 
-	v, _ := json.Marshal(data)
-
 	m := md5.New()
 
 	sb := strings.Builder{}
@@ -26,7 +24,14 @@ func CheckSign(appID, appKey, random, sign string, ts int, data interface{}) boo
 	sb.WriteByte('-')
 	sb.WriteString(cast.ToString(ts))
 	sb.WriteByte('-')
-	sb.Write(v)
+
+	if val, ok := data.(string); ok {
+		sb.WriteString(val)
+	} else {
+		val, _ := json.Marshal(data)
+		sb.Write(val)
+	}
+
 	sb.WriteByte('-')
 	sb.WriteString(random)
 	sb.WriteByte('-')
@@ -44,8 +49,6 @@ func Sign(appID, appKey string, data interface{}) (sign string, random string, t
 
 	ts = int(time.Now().Unix())
 
-	v, _ := json.Marshal(data)
-
 	m := md5.New()
 
 	sb := strings.Builder{}
@@ -53,7 +56,14 @@ func Sign(appID, appKey string, data interface{}) (sign string, random string, t
 	sb.WriteByte('-')
 	sb.WriteString(cast.ToString(ts))
 	sb.WriteByte('-')
-	sb.Write(v)
+
+	if val, ok := data.(string); ok {
+		sb.WriteString(val)
+	} else {
+		val, _ := json.Marshal(data)
+		sb.Write(val)
+	}
+
 	sb.WriteByte('-')
 	sb.WriteString(random)
 	sb.WriteByte('-')