diff --git a/Documentation/Examples/boundary_example.cc b/Documentation/Examples/boundary_example.cc
index ff4885b378251e0e93e3137c5357dc0f1858d211..7b990016bbcb4e2a2a0794fddf16aa2a92399d37 100644
--- a/Documentation/Examples/boundary_example.cc
+++ b/Documentation/Examples/boundary_example.cc
@@ -99,7 +99,6 @@ int main() {
   auto outerMedium = EnvType::CreateNode<Sphere>(
       Point{rootCS, 0_m, 0_m, 0_m}, 1_km * std::numeric_limits<double>::infinity());
 
-  // fraction of oxygen
   auto const props =
       outerMedium
           ->SetModelProperties<environment::HomogeneousMedium<setup::IEnvironmentModel>>(