diff --git a/url.go b/url.go
index c667e7c..f699868 100644
--- a/url.go
+++ b/url.go
@@ -13,6 +13,8 @@ import (
 	ikurl "github.com/imagekit-developer/imagekit-go/url"
 )
 
+const DEFAULT_TIMESTAMP = 9999999999
+
 // Url generates url from UrlParam
 func (ik *ImageKit) Url(params ikurl.UrlParam) (string, error) {
 	var resultUrl string
@@ -81,18 +83,29 @@ func (ik *ImageKit) Url(params ikurl.UrlParam) (string, error) {
 			now = params.UnixTime()
 		}
 
-		var expires = strconv.FormatInt(now+int64(params.ExpireSeconds), 10)
+		var expires string
+		if params.ExpireSeconds > 0 {
+			expires = strconv.FormatInt(now+int64(params.ExpireSeconds), 10)
+		} else {
+			expires = strconv.Itoa(DEFAULT_TIMESTAMP)
+		}
 		var path = strings.Replace(resultUrl, endpoint, "", 1)
-
 		path = path + expires
 		mac := hmac.New(sha1.New, []byte(ik.Config.Cloud.PrivateKey))
 		mac.Write([]byte(path))
 		signature := hex.EncodeToString(mac.Sum(nil))
-
 		if strings.Index(resultUrl, "?") > -1 {
-			resultUrl = resultUrl + "&" + fmt.Sprintf("ik-t=%s&ik-s=%s", expires, signature)
+			if params.ExpireSeconds > 0 && params.ExpireSeconds != DEFAULT_TIMESTAMP {
+				resultUrl = resultUrl + "&" + fmt.Sprintf("ik-t=%s&ik-s=%s", expires, signature)
+			} else {
+				resultUrl = resultUrl + "&" + fmt.Sprintf("ik-s=%s", signature)
+			}
 		} else {
-			resultUrl = resultUrl + "?" + fmt.Sprintf("ik-t=%s&ik-s=%s", expires, signature)
+			if params.ExpireSeconds > 0 && params.ExpireSeconds != DEFAULT_TIMESTAMP {
+				resultUrl = resultUrl + "?" + fmt.Sprintf("ik-t=%s&ik-s=%s", expires, signature)
+			} else {
+				resultUrl = resultUrl + "?" + fmt.Sprintf("ik-s=%s", signature)
+			}
 		}
 	}