diff --git a/src/main/java/com/tencentyun/TLSSigAPIv2.java b/src/main/java/com/tencentyun/TLSSigAPIv2.java
index bcf1878..316d9d2 100755
--- a/src/main/java/com/tencentyun/TLSSigAPIv2.java
+++ b/src/main/java/com/tencentyun/TLSSigAPIv2.java
@@ -172,11 +172,13 @@ public byte[] genUserBuf(String account, long dwAuthID, long dwExpTime,
         int roomStrLength = RoomStr.length();
         int offset = 0;
         int bufLength = 1 + 2 + accountLength + 20 ;
+        if (roomStrLength > 0) {
+            bufLength = bufLength + 2 + roomStrLength;
+        }
         byte[] userbuf = new byte[bufLength];
 
         //cVer
         if (roomStrLength > 0) {
-            bufLength = bufLength + 2 + roomStrLength;
             userbuf[offset++] = 1;
         } else {
             userbuf[offset++] = 0;
diff --git a/src/test/com/tencentyun/TLSSigAPITest.java b/src/test/com/tencentyun/TLSSigAPITest.java
index 17f40aa..631d3b1 100755
--- a/src/test/com/tencentyun/TLSSigAPITest.java
+++ b/src/test/com/tencentyun/TLSSigAPITest.java
@@ -36,6 +36,12 @@ public void testGenSigWithUserBug() {
         TLSSigAPIv2 api = new TLSSigAPIv2(1400000000, "5bd2850fff3ecb11d7c805251c51ee463a25727bddc2385f3fa8bfee1bb93b5e");
         System.out.println(api.genPrivateMapKey("xiaojun", 180 * 86400, 10000, 255));
     }
+    //使用userbuf和字符串房间号生产privatemapkey
+    @Test
+    public void testGenSigWithUserBug() {
+        TLSSigAPIv2 api = new TLSSigAPIv2(1400000000, "5bd2850fff3ecb11d7c805251c51ee463a25727bddc2385f3fa8bfee1bb93b5e");
+        System.out.println(api.genPrivateMapKeyWithStringRoomID("xiaojun", 180 * 86400, "100000000", 255));
+    }
 
     /**
      * Method: hmacsha256(String identifier, long currTime, long expire)
diff --git a/tls-sig-api-v2-java.iml b/tls-sig-api-v2-java.iml
new file mode 100644
index 0000000..48426fc
--- /dev/null
+++ b/tls-sig-api-v2-java.iml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager">
+    <output url="file://$MODULE_DIR$/bin" />
+    <exclude-output />
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file