diff --git a/mindplot/src/main/javascript/RestPersistenceManager.js b/mindplot/src/main/javascript/RestPersistenceManager.js
index e3535408..1a6f7564 100644
--- a/mindplot/src/main/javascript/RestPersistenceManager.js
+++ b/mindplot/src/main/javascript/RestPersistenceManager.js
@@ -43,8 +43,8 @@ mindplot.RESTPersistenceManager = new Class({
 
             var persistence = this;
             var query = "minor=" + !saveHistory;
-            query = query + (this.timestamp ? "&timestamp=" + this.timestamp : "");
-            query = query + (this.session ? "&session=" + this.session : "");
+            query = query + "&timestamp=" + this.timestamp;
+            query = query + "&session=" + this.session;
 
             if (!persistence.onSave) {
 
diff --git a/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java b/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
index e815f0f9..d9edf802 100644
--- a/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
+++ b/wise-webapp/src/main/java/com/wisemapping/rest/MindmapController.java
@@ -169,7 +169,7 @@ public class MindmapController extends BaseController {
 
         // Update edition timeout ...
         final LockManager lockManager = mindmapService.getLockManager();
-        final LockInfo lockInfo = lockManager.updateExpirationTimeout(mindmap, user, session);
+        final LockInfo lockInfo = lockManager.updateExpirationTimeout(mindmap, user);
         return lockInfo.getTimestamp();
     }
 
@@ -192,11 +192,10 @@ public class MindmapController extends BaseController {
                     throw new SessionExpiredException(lastEditor);
                 }
             } else if (outdated) {
-                throw new MultipleSessionsOpenException("Sessions:" + session + ":" + lockInfo.getSession() + "Timestamp: " + timestamp + ": " + lockInfo.getTimestamp());
+                throw new MultipleSessionsOpenException("Sessions:" + session + ":" + lockInfo.getSession() + ",Timestamp: " + timestamp + ": " + lockInfo.getTimestamp());
             }
         } else {
             throw new SessionExpiredException(lockInfo.getUser());
-
         }
     }
 
diff --git a/wise-webapp/src/main/java/com/wisemapping/service/LockInfo.java b/wise-webapp/src/main/java/com/wisemapping/service/LockInfo.java
index 02131b0d..5a998b8a 100644
--- a/wise-webapp/src/main/java/com/wisemapping/service/LockInfo.java
+++ b/wise-webapp/src/main/java/com/wisemapping/service/LockInfo.java
@@ -36,6 +36,7 @@ public class LockInfo {
         this.user = user;
         this.updateTimeout();
         this.updateTimestamp(mindmap);
+        this.session = session;
     }
 
     public User getUser() {
diff --git a/wise-webapp/src/main/java/com/wisemapping/service/LockManager.java b/wise-webapp/src/main/java/com/wisemapping/service/LockManager.java
index c0ee588e..ecfae08c 100644
--- a/wise-webapp/src/main/java/com/wisemapping/service/LockManager.java
+++ b/wise-webapp/src/main/java/com/wisemapping/service/LockManager.java
@@ -30,13 +30,15 @@ public interface LockManager {
 
     LockInfo getLockInfo(@NotNull Mindmap mindmap);
 
-    LockInfo updateExpirationTimeout(@NotNull Mindmap mindmap, @NotNull User user,long session);
+    LockInfo updateExpirationTimeout(@NotNull Mindmap mindmap, @NotNull User user);
 
     void unlock(@NotNull Mindmap mindmap, @NotNull User user) throws LockException, AccessDeniedSecurityException;
 
     boolean isLockedBy(@NotNull Mindmap mindmap, @NotNull User collaborator);
 
+    @NotNull
     LockInfo lock(@NotNull Mindmap mindmap, @NotNull User user, long session) throws WiseMappingException;
 
-    long generateSession();
+    @NotNull
+    LockInfo lock(@NotNull Mindmap mindmap, @NotNull User user) throws WiseMappingException;
 }
diff --git a/wise-webapp/src/main/java/com/wisemapping/service/LockManagerImpl.java b/wise-webapp/src/main/java/com/wisemapping/service/LockManagerImpl.java
index e60329e1..c705abbc 100644
--- a/wise-webapp/src/main/java/com/wisemapping/service/LockManagerImpl.java
+++ b/wise-webapp/src/main/java/com/wisemapping/service/LockManagerImpl.java
@@ -63,7 +63,7 @@ class LockManagerImpl implements LockManager {
     }
 
     @Override
-    public LockInfo updateExpirationTimeout(@NotNull Mindmap mindmap, @NotNull User user, long session) {
+    public LockInfo updateExpirationTimeout(@NotNull Mindmap mindmap, @NotNull User user) {
         if (!this.isLocked(mindmap)) {
             throw new IllegalStateException("Lock lost for map. No update possible.");
         }
@@ -74,9 +74,8 @@ class LockManagerImpl implements LockManager {
         }
 
         result.updateTimeout();
-        result.setSession(session);
         result.updateTimestamp(mindmap);
-//        logger.debug("Timeout updated for:" + mindmap.getId());
+        logger.debug("Timeout updated for:" + mindmap.getId());
         return result;
     }
 
@@ -108,6 +107,13 @@ class LockManagerImpl implements LockManager {
         return result;
     }
 
+
+    @Override
+    @NotNull
+    public LockInfo lock(@NotNull Mindmap mindmap, @NotNull User user) throws WiseMappingException {
+        return this.lock(mindmap, user, System.nanoTime());
+    }
+
     @Override
     @NotNull
     public LockInfo lock(@NotNull Mindmap mindmap, @NotNull User user, long session) throws WiseMappingException {
@@ -123,7 +129,8 @@ class LockManagerImpl implements LockManager {
         if (result != null) {
             // Update timeout only...
             logger.debug("Update timestamp:" + mindmap.getId());
-            updateExpirationTimeout(mindmap, user, session);
+            updateExpirationTimeout(mindmap, user);
+            result.setSession(session);
         } else {
             logger.debug("Lock map id:" + mindmap.getId());
             result = new LockInfo(user, mindmap, session);
@@ -132,11 +139,6 @@ class LockManagerImpl implements LockManager {
         return result;
     }
 
-    @Override
-    public long generateSession() {
-        return System.nanoTime();
-    }
-
     public LockManagerImpl() {
         lockInfoByMapId = new ConcurrentHashMap<Integer, LockInfo>();
         expirationTimer.schedule(new TimerTask() {
diff --git a/wise-webapp/src/main/java/com/wisemapping/webmvc/MindmapController.java b/wise-webapp/src/main/java/com/wisemapping/webmvc/MindmapController.java
index 8e8c8f13..e38343de 100644
--- a/wise-webapp/src/main/java/com/wisemapping/webmvc/MindmapController.java
+++ b/wise-webapp/src/main/java/com/wisemapping/webmvc/MindmapController.java
@@ -46,6 +46,7 @@ import java.util.Locale;
 public class MindmapController {
 
 
+    public static final String LOCK_SESSION_ATTRIBUTE = "lockSession";
     @Qualifier("mindmapService")
     @Autowired
     private MindmapService mindmapService;
@@ -160,10 +161,9 @@ public class MindmapController {
                 readOnlyMode = true;
                 model.addAttribute("mindmapLocked",true);
             } else {
-                final long session = lockManager.generateSession();
-                final LockInfo lock = lockManager.lock(mindmap, collaborator, session);
+                final LockInfo lock = lockManager.lock(mindmap, collaborator);
                 model.addAttribute("lockTimestamp", lock.getTimestamp());
-                model.addAttribute("lockSession", session);
+                model.addAttribute(LOCK_SESSION_ATTRIBUTE, lock.getSession());
             }
             model.addAttribute("lockInfo", lockManager.getLockInfo(mindmap));
         }