diff --git a/AIStudio.Wpf.DiagramDesigner/Helpers/DrawingHelper.cs b/AIStudio.Wpf.DiagramDesigner/Helpers/DrawingHelper.cs
index ec068ea..c3aa727 100644
--- a/AIStudio.Wpf.DiagramDesigner/Helpers/DrawingHelper.cs
+++ b/AIStudio.Wpf.DiagramDesigner/Helpers/DrawingHelper.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Numerics;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
@@ -77,16 +78,20 @@ namespace AIStudio.Wpf.DiagramDesigner
 
             var radian = Math.Atan2(endPoint.Y - startPoint.Y, endPoint.X - startPoint.X);
             var angle = radian * 180 / Math.PI;
-            if (angle >= -90 && angle < 90)
-            {
-                return 90 - angle;
-                
-            }
-            else
-            {
-                return angle - 90;
-            }
+
+
+            return ConvertToPositive360(90 - angle);
+
         }
 
+        static double ConvertToPositive360(double angle)
+        {
+            double positiveAngle = angle % 360;
+            if (positiveAngle < 0)
+            {
+                positiveAngle += 360;
+            }
+            return positiveAngle;
+        }
     }
 }