diff --git a/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.cxx b/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.cxx
index 5fb4fa255ab63f1d3b0af168f9804836d6041ac4..7bbf88afc6f63f4aca266cae78ed134643925be7 100644
--- a/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.cxx
+++ b/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.cxx
@@ -532,11 +532,16 @@ int vtkMRMLMarkupsNode::AddPointWorldToNewMarkup(vtkVector3d pointWorld, std::st
 //-----------------------------------------------------------
 int vtkMRMLMarkupsNode::AddPointToNthMarkup(vtkVector3d point, int n)
 {
-  int pointIndex = 0;
-  if (this->MarkupExists(n))
+  if (!this->MarkupExists(n))
     {
-    this->Markups[n].points.push_back(point);
+    return -1;
     }
+
+  this->Markups[n].points.push_back(point);
+  this->Modified();
+  int pointIndex = static_cast<int>(this->Markups[n].points.size() - 1);
+  this->InvokeCustomModifiedEvent(
+    vtkMRMLMarkupsNode::NthMarkupModifiedEvent, (void*)&pointIndex);
   return pointIndex;
 }
 
diff --git a/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.h b/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.h
index a01df2bfb1b92d3cc02e81665a0ceed8dd54dd76..6993ebb5a01041ef44a1261a3a5e56b29a35c9ca 100644
--- a/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.h
+++ b/Modules/Loadable/Markups/MRML/vtkMRMLMarkupsNode.h
@@ -191,7 +191,7 @@ public:
   /// Create a new markup with one point, defined in the world coordinate system.
   /// Return index of new markup, -1 on failure.
   int AddPointWorldToNewMarkup(vtkVector3d point, std::string label = std::string());
-  /// Add a point to the nth markup, returning the point index
+  /// Add a point to the nth markup, returning the point index, -1 on failure.
   int AddPointToNthMarkup(vtkVector3d point, int n);
 
   /// Get the position of the pointIndex'th point in markupIndex markup,