diff --git a/src/wkb2gltf.core/GlbCreator.cs b/src/wkb2gltf.core/GlbCreator.cs
index b8e8e76f..35cdcd9c 100644
--- a/src/wkb2gltf.core/GlbCreator.cs
+++ b/src/wkb2gltf.core/GlbCreator.cs
@@ -6,6 +6,7 @@
 using SharpGLTF.Geometry.VertexTypes;
 using SharpGLTF.Materials;
 using SharpGLTF.Scenes;
+using SharpGLTF.Schema2;
 using Wkb2Gltf.extensions;
 using Wkb2Gltf.Extensions;
 
@@ -60,6 +61,7 @@ public static byte[] GetGlb(List<List<Triangle>> triangles, string copyright = "
         model.LogicalNodes.First().LocalTransform = new SharpGLTF.Transforms.AffineTransform(localTransform);
 
         if (addOutlines) {
+            CesiumExtensions.RegisterExtensions();
             foreach (var primitive in model.LogicalMeshes[0].Primitives) {
                 primitive.AddOutlines();
             }
diff --git a/src/wkb2gltf.core/wkb2gltf.csproj b/src/wkb2gltf.core/wkb2gltf.csproj
index cf6154d7..458ff15d 100644
--- a/src/wkb2gltf.core/wkb2gltf.csproj
+++ b/src/wkb2gltf.core/wkb2gltf.csproj
@@ -11,10 +11,11 @@
     <PackageReference Include="b3dm-tile" Version="1.1.1" />
     <PackageReference Include="bertt.triangulator" Version="1.2.3" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+    <PackageReference Include="SharpGLTF.Cesium" Version="1.0.0-cesiummetadata3" />
     <PackageReference Include="System.Drawing.Common" Version="7.0.0" />
     <PackageReference Include="System.Drawing.Primitives" Version="4.3.0" />
     <PackageReference Include="System.Numerics.Vectors" Version="4.6.0-preview5.19224.8" />
     <PackageReference Include="Wkx" Version="0.5.1" />
-	<PackageReference Include="SharpGLTF.Toolkit" Version="1.0.0-cesiummetadata" />
+	<PackageReference Include="SharpGLTF.Toolkit" Version="1.0.0-cesiummetadata3" />
   </ItemGroup>
 </Project>