diff --git a/src/Add-on/closetest.ts b/src/Add-on/closetest.ts
index ef851e3d5..59431e477 100644
--- a/src/Add-on/closetest.ts
+++ b/src/Add-on/closetest.ts
@@ -1,6 +1,6 @@
 import { Command } from "../Editor/CommandMachine";
 import { app } from "../ApplicationServices/Application";
-import { Line } from "../DatabaseServices/Line";
+import { Line } from '../DatabaseServices/Line';
 import { Curve, ExtendType } from "../DatabaseServices/Curve";
 import { PromptStatus } from "../Editor/PromptResult";
 import { Polyline } from "../DatabaseServices/Polyline";
@@ -18,7 +18,9 @@ export class Command_ClosePt implements Command
         {
             let cu = cuRes.Entity as Curve;
             let line = new Line();
+            let derLine = new Line();
             app.m_Database.ModelSpace.Append(line);
+            app.m_Database.ModelSpace.Append(derLine);
 
             let extend = false;
             while (true)
@@ -31,6 +33,9 @@ export class Command_ClosePt implements Command
                         line.StartPoint = p;
 
                         line.EndPoint = cu.GetClosestPointTo(p, extend);
+
+                        derLine.StartPoint = line.EndPoint;
+                        derLine.EndPoint = line.EndPoint.add(cu.GetFistDeriv(line.EndPoint));
                     }
                 })
                 if (p.Status === PromptStatus.Keyword)