diff --git a/OpenNest.Core/Geometry/EllipseConverter.cs b/OpenNest.Core/Geometry/EllipseConverter.cs
index 0163fbb..8f6d8a8 100644
--- a/OpenNest.Core/Geometry/EllipseConverter.cs
+++ b/OpenNest.Core/Geometry/EllipseConverter.cs
@@ -108,8 +108,18 @@ namespace OpenNest.Geometry
                     nameof(tolerance),
                     "Tolerance must be positive."
                 );
-            if (semiMajor <= 0 || semiMinor <= 0)
-                throw new ArgumentOutOfRangeException("Semi-axis lengths must be positive.");
+            if (semiMajor <= 0)
+                throw new ArgumentOutOfRangeException(
+                    nameof(semiMajor),
+                    semiMajor,
+                    "Semi-major axis length must be positive."
+                );
+            if (semiMinor <= 0)
+                throw new ArgumentOutOfRangeException(
+                    nameof(semiMinor),
+                    semiMinor,
+                    "Semi-minor axis length must be positive."
+                );
 
             if (endParam <= startParam)
                 endParam += Angle.TwoPI;
diff --git a/OpenNest.Tests/Geometry/EllipseArgumentValidationTests.cs b/OpenNest.Tests/Geometry/EllipseArgumentValidationTests.cs
new file mode 100644
index 0000000..8672c94
--- /dev/null
+++ b/OpenNest.Tests/Geometry/EllipseArgumentValidationTests.cs
@@ -0,0 +1,46 @@
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Tests.Geometry;
+
+public class EllipseArgumentValidationTests
+{
+    [Theory]
+    [InlineData(0.0, 5.0, "semiMajor", 0.0)]
+    [InlineData(-3.0, 5.0, "semiMajor", -3.0)]
+    [InlineData(10.0, 0.0, "semiMinor", 0.0)]
+    [InlineData(10.0, -2.0, "semiMinor", -2.0)]
+    [InlineData(0.0, 0.0, "semiMajor", 0.0)]
+    [InlineData(0.0, -2.0, "semiMajor", 0.0)]
+    [InlineData(-3.0, 0.0, "semiMajor", -3.0)]
+    [InlineData(-3.0, -2.0, "semiMajor", -3.0)]
+    public void Convert_NonpositiveAxes_IdentifiesFirstInvalidAxis(
+        double semiMajor,
+        double semiMinor,
+        string expectedName,
+        double expectedValue
+    )
+    {
+        var error = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            EllipseConverter.Convert(new Vector(0, 0), semiMajor, semiMinor, 0, 0, Angle.TwoPI)
+        );
+
+        Assert.Equal(expectedName, error.ParamName);
+        Assert.Equal(expectedValue, Assert.IsType<double>(error.ActualValue));
+        Assert.Contains("positive", error.Message);
+    }
+
+    [Theory]
+    [InlineData(0.0)]
+    [InlineData(-0.01)]
+    public void Convert_InvalidToleranceAndAxes_ValidatesToleranceFirst(double tolerance)
+    {
+        var error = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            EllipseConverter.Convert(new Vector(0, 0), -3, -2, 0, 0, Angle.TwoPI, tolerance)
+        );
+
+        Assert.Equal(nameof(tolerance), error.ParamName);
+        Assert.Null(error.ActualValue);
+        Assert.Contains("Tolerance must be positive.", error.Message);
+    }
+}