diff --git a/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelMaterialConverter.hpp b/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelMaterialConverter.hpp
index 3e19df13c94..bde01e92f60 100644
--- a/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelMaterialConverter.hpp
+++ b/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelMaterialConverter.hpp
@@ -5,15 +5,15 @@
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 #pragma once
 
 #include "Acts/Material/Material.hpp"
 
 class GeoMaterial;
 
-namespace Acts {
+namespace Acts::GeoModel {
 
-namespace GeoModel {
 /// @brief Convert GeoMaterial to Acts::Material
 ///
 /// @param gm The GeoMaterial to be converted
@@ -21,5 +21,4 @@ namespace GeoModel {
 Material geoMaterialConverter(const GeoMaterial* gm,
                               bool useMolarDensity = true);
 
-}  // namespace GeoModel
-}  // namespace Acts
+}  // namespace Acts::GeoModel
diff --git a/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelToDetectorVolume.hpp b/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelToDetectorVolume.hpp
index 118bbc4749b..e71863a49b6 100644
--- a/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelToDetectorVolume.hpp
+++ b/Plugins/GeoModel/include/Acts/Plugins/GeoModel/GeoModelToDetectorVolume.hpp
@@ -5,6 +5,7 @@
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 #pragma once
 
 #include "Acts/Detector/DetectorVolume.hpp"
@@ -13,9 +14,8 @@
 
 class GeoShape;
 
-namespace Acts {
+namespace Acts::GeoModel {
 
-namespace GeoModel {
 /// @brief Convert a GeoModel shape to a DetectorVolume
 ///
 /// @param shape the GeoModel shape
@@ -24,5 +24,5 @@ namespace GeoModel {
 std::shared_ptr<Experimental::DetectorVolume> convertVolume(
     const GeometryContext& context, const GeoShape* shape,
     const std::string& name, const GeoTrf::Transform3D transform);
-}  // namespace GeoModel
-}  // namespace Acts
+
+}  // namespace Acts::GeoModel
diff --git a/Plugins/GeoModel/src/GeoModelToDetectorVolume.cpp b/Plugins/GeoModel/src/GeoModelToDetectorVolume.cpp
index 74059936230..2b567337f2e 100644
--- a/Plugins/GeoModel/src/GeoModelToDetectorVolume.cpp
+++ b/Plugins/GeoModel/src/GeoModelToDetectorVolume.cpp
@@ -27,8 +27,8 @@
 #include <GeoModelKernel/GeoTube.h>
 #include <GeoModelKernel/GeoTubs.h>
 
-namespace Acts {
-namespace GeoModel {
+namespace Acts::GeoModel {
+
 std::shared_ptr<Experimental::DetectorVolume> convertVolume(
     const GeometryContext& context, const GeoShape* shape,
     const std::string& name, const GeoTrf::Transform3D transform) {
@@ -164,5 +164,5 @@ std::shared_ptr<Experimental::DetectorVolume> convertVolume(
   }
   throw std::runtime_error("FATAL: Unsupported GeoModel shape");
 }
-}  // namespace GeoModel
-}  // namespace Acts
+
+}  // namespace Acts::GeoModel