diff --git a/CADability/BSpline2D.cs b/CADability/BSpline2D.cs
index 501b8b54..0ded13f9 100644
--- a/CADability/BSpline2D.cs
+++ b/CADability/BSpline2D.cs
@@ -1668,10 +1668,9 @@ public override void AddToGraphicsPath(System.Drawing.Drawing2D.GraphicsPath pat
             // Notfalls Darstellung als Polyline
             int l = poles.Length * 4 + 2;
             PointF[] ppf = new PointF[l];
-            double du = (endParam - startParam) / (l - 1);
             for (int i = 0; i < l; ++i)
             {
-                ppf[i] = PointAt(startParam + i * du).PointF;
+                ppf[i] = PointAt((double)i / (l - 1)).PointF; // PointAt expects 0..1, not the knot parameter
             }
             if (!forward) Array.Reverse(ppf);
             path.AddLines(ppf);
diff --git a/tests/CADability.Tests/BSpline2DGraphicsPathTests.cs b/tests/CADability.Tests/BSpline2DGraphicsPathTests.cs
new file mode 100644
index 00000000..236ccf5c
--- /dev/null
+++ b/tests/CADability.Tests/BSpline2DGraphicsPathTests.cs
@@ -0,0 +1,31 @@
+#if WINDOWS
+using CADability.Curve2D;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Drawing;
+using System.Drawing.Drawing2D;
+
+namespace CADability.Tests
+{
+    /// <summary>
+    /// <see cref="BSpline2D.AddToGraphicsPath"/> passed knot parameters to <see cref="BSpline2D.PointAt"/>, which expects
+    /// 0..1, so a spline whose knots do not run from 0 to 1 was drawn through wrong points. GDI+ only works on Windows, so
+    /// this test only runs there.
+    /// </summary>
+    [TestClass]
+    public class BSpline2DGraphicsPathTests
+    {
+        [TestMethod]
+        public void ASplineWithKnotsBeyondOneIsSampledOnTheCurve()
+        {
+            BSpline2D bsp = new BSpline2D(new[] { new GeoPoint2D(0, 0), new GeoPoint2D(1, 3), new GeoPoint2D(4, 3), new GeoPoint2D(5, 0) }, null, new double[] { 0, 5 }, new[] { 4, 4 }, 3, false, 0, 5);
+            GraphicsPath path = new GraphicsPath();
+            bsp.AddToGraphicsPath(path, true);
+            PointF[] points = path.PathPoints;
+            Assert.AreEqual(bsp.StartPoint.PointF, points[0]);
+            Assert.AreEqual(bsp.EndPoint.PointF, points[points.Length - 1]);
+            // MinDistance and not Distance: BSpline2D.Distance returns double.MaxValue for these points
+            foreach (PointF p in points) Assert.AreEqual(0.0, bsp.MinDistance(new GeoPoint2D(p.X, p.Y)), 1e-4);
+        }
+    }
+}
+#endif