diff --git a/NiflySharp/NifFile.cs b/NiflySharp/NifFile.cs
index 75a912d..43a2f4e 100644
--- a/NiflySharp/NifFile.cs
+++ b/NiflySharp/NifFile.cs
@@ -1970,7 +1970,8 @@ public NifFileOptimizeResult OptimizeFor(NifFileOptimizeOptions options)
                     bsOptShape.Rotation = shape.Rotation;
                     bsOptShape.Scale = shape.Scale;
 
-                    bsOptShape.Create(Header.Version, geomData.Vertices, geomData.Triangles, geomData.UVSets, geomData.Normals);
+                    // Honor the withoutNormals flag — ModelSpace shaders must drop normals.
+                    bsOptShape.Create(Header.Version, geomData.Vertices, geomData.Triangles, geomData.UVSets, !withoutNormals ? geomData.Normals : null);
                     bsOptShape.Flags_ui = shape.Flags_ui;
 
                     // Restore old bounds for static meshes or when calc bounds is off