diff --git a/src/main/resources/update/1_1.sql b/src/main/resources/update/1_1.sql
new file mode 100644
index 0000000..9cfd50a
--- /dev/null
+++ b/src/main/resources/update/1_1.sql
@@ -0,0 +1,8 @@
+-- Fix COLLABORATOR constraints
+ALTER TABLE COLLABORATOR DROP CONSTRAINT IDX_COLLABORATOR_FK1 IF EXISTS;
+ALTER TABLE COLLABORATOR DROP CONSTRAINT IDX_COLLABORATOR_FK0 IF EXISTS;
+ALTER TABLE COLLABORATOR DROP CONSTRAINT IDX_COLLABORATOR_PK IF EXISTS;
+
+ALTER TABLE COLLABORATOR ADD CONSTRAINT IDX_COLLABORATOR_PK PRIMARY KEY (USER_NAME, REPOSITORY_NAME, COLLABORATOR_NAME);
+ALTER TABLE COLLABORATOR ADD CONSTRAINT IDX_COLLABORATOR_FK0 FOREIGN KEY (USER_NAME, REPOSITORY_NAME) REFERENCES REPOSITORY (USER_NAME, REPOSITORY_NAME);
+ALTER TABLE COLLABORATOR ADD CONSTRAINT IDX_COLLABORATOR_FK1 FOREIGN KEY (COLLABORATOR_NAME) REFERENCES ACCOUNT (USER_NAME);
diff --git a/src/main/scala/servlet/AutoUpdateListener.scala b/src/main/scala/servlet/AutoUpdateListener.scala
index aa48a00..5453c22 100644
--- a/src/main/scala/servlet/AutoUpdateListener.scala
+++ b/src/main/scala/servlet/AutoUpdateListener.scala
@@ -14,7 +14,7 @@
    * Version of GitBucket
    * 
    * @param majorVersion the major version
-   * @param minorVersion the minor version
+   * @param minorVersion the minor version
    */
   case class Version(majorVersion: Int, minorVersion: Int){
     
@@ -22,7 +22,7 @@
     
     /**
      * Execute update/MAJOR_MINOR.sql to update schema to this version.
-     * If corresponding SQL file does not exist, this method do nothing.
+     * If corresponding SQL file does not exist, this method do nothing.
      */
     def update(conn: Connection): Unit = {
       val sqlPath = "update/%d_%d.sql".format(majorVersion, minorVersion)
@@ -40,7 +40,7 @@
     }
     
     /**
-     * MAJOR.MINOR
+     * MAJOR.MINOR
      */
     val versionString = "%d.%d".format(majorVersion, minorVersion)
   }
@@ -49,6 +49,7 @@
    * The history of versions. A head of this sequence is the current BitBucket version.
    */
   val versions = Seq(
+      Version(1, 1),
       Version(1, 0)
   )
   
@@ -84,7 +85,7 @@
 }
 
 /**
- * Start H2 database and update schema automatically.
+ * Start H2 database and update schema automatically.
  */
 class AutoUpdateListener extends org.h2.server.web.DbStarter {
   import AutoUpdate._