diff --git a/tests/ImageSharp.Tests/Formats/WebP/WebpVp8XTests.cs b/tests/ImageSharp.Tests/Formats/WebP/WebpVp8XTests.cs
new file mode 100644
index 0000000000..78be0bf9fd
--- /dev/null
+++ b/tests/ImageSharp.Tests/Formats/WebP/WebpVp8XTests.cs
@@ -0,0 +1,26 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using SixLabors.ImageSharp.Formats.Webp.Chunks;
+
+namespace SixLabors.ImageSharp.Tests.Formats.WebP;
+
+[Trait("Format", "Webp")]
+public class WebpVp8XTests
+{
+    [Fact]
+    public void WebpVp8X_WriteTo_Writes_Reserved_Bytes()
+    {
+        // arrange
+        WebpVp8X header = new(false, false, false, false, false, 10, 40);
+        MemoryStream ms = new();
+        byte[] expected = [86, 80, 56, 88, 10, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 39, 0, 0];
+
+        // act
+        header.WriteTo(ms);
+
+        // assert
+        byte[] actual = ms.ToArray();
+        Assert.Equal(expected, actual);
+    }
+}