diff --git a/apps/common/main/lib/controller/ReviewChanges.js b/apps/common/main/lib/controller/ReviewChanges.js
index fdfda5bd5b..289cdd0bd8 100644
--- a/apps/common/main/lib/controller/ReviewChanges.js
+++ b/apps/common/main/lib/controller/ReviewChanges.js
@@ -124,6 +124,8 @@ define([
                 if (this.appConfig.canReview || this.appConfig.canViewReview) {
                     this.api.asc_registerCallback('asc_onShowRevisionsChange', _.bind(this.onApiShowChange, this));
                     this.api.asc_registerCallback('asc_onUpdateRevisionsChangesPosition', _.bind(this.onApiUpdateChangePosition, this));
+                    this.api.asc_registerCallback('asc_onAuthParticipantsChanged', _.bind(this.onAuthParticipantsChanged, this));
+                    this.api.asc_registerCallback('asc_onParticipantsChanged',     _.bind(this.onAuthParticipantsChanged, this));
                 }
                 this.api.asc_registerCallback('asc_onAcceptChangesBeforeCompare',_.bind(this.onAcceptChangesBeforeCompare, this));
                 this.api.asc_registerCallback('asc_onCoAuthoringDisconnect',_.bind(this.onCoAuthoringDisconnect, this));
@@ -856,6 +858,17 @@ define([
             });
         },
 
+        onAuthParticipantsChanged: function(users) {
+            if (this.view && this.view.btnCompare) {
+                var length = 0;
+                _.each(users, function(item){
+                    if (!item.asc_getView())
+                        length++;
+                });
+                this.view.btnCompare.setDisabled(length>1 || this.viewmode);
+            }
+        },
+
         textInserted: '<b>Inserted:</b>',
         textDeleted: '<b>Deleted:</b>',
         textParaInserted: '<b>Paragraph Inserted</b> ',