diff --git a/lunar.js b/lunar.js
index 16001af..f9c185d 100644
--- a/lunar.js
+++ b/lunar.js
@@ -1281,7 +1281,7 @@
             monthIndex += 12;
           }
           var index = start-monthIndex-1;
-          if(index<0){
+          while(index<0){
             index += 9;
           }
           return NineStar.fromIndex(index);
diff --git a/package.json b/package.json
index 1be2c56..a00bc88 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lunar-javascript",
-  "version": "1.0.25",
+  "version": "1.0.26",
   "description": "lunar is a calendar library for Solar and Chinese Lunar.",
   "main": "index.js",
   "scripts": {