diff --git a/Processes/NullModel/NullModel.cc b/Processes/NullModel/NullModel.cc
index c99a464b4dd4eca06e288df524202ec8016bd3e3..802ee5b4a669f824ac94c717e0bd61b3a0cfd3a3 100644
--- a/Processes/NullModel/NullModel.cc
+++ b/Processes/NullModel/NullModel.cc
@@ -14,21 +14,23 @@
 #include <corsika/setup/SetupTrajectory.h>
 
 using namespace corsika;
-using namespace corsika::process::null_model;
+namespace corsika::process::null_model {
 
-void corsika::process::null_model::NullModel::Init() {}
+  void NullModel::Init() {}
 
-NullModel::NullModel(units::si::LengthType maxStepLength)
-    : fMaxStepLength(maxStepLength) {}
+  NullModel::NullModel(units::si::LengthType maxStepLength)
+      : fMaxStepLength(maxStepLength) {}
 
-template <>
-process::EProcessReturn NullModel::DoContinuous(setup::Stack::ParticleType&,
-                                                setup::Trajectory&, setup::Stack&) const {
-  return process::EProcessReturn::eOk;
-}
+  template <>
+  process::EProcessReturn NullModel::DoContinuous(setup::Stack::ParticleType&,
+                                                  setup::Trajectory&) const {
+    return process::EProcessReturn::eOk;
+  }
 
-template <>
-units::si::LengthType NullModel::MaxStepLength(setup::Stack::ParticleType&,
-                                               setup::Trajectory&) const {
-  return fMaxStepLength;
-}
+  template <>
+  units::si::LengthType NullModel::MaxStepLength(setup::Stack::ParticleType&,
+                                                 setup::Trajectory&) const {
+    return fMaxStepLength;
+  }
+
+} // namespace corsika::process::null_model
diff --git a/Processes/NullModel/NullModel.h b/Processes/NullModel/NullModel.h
index 5579d69f8a1ec08348e242e4d5bb8d012a21feb5..db157b55fefdc1ed584eb7f7437bc45d9d2986b0 100644
--- a/Processes/NullModel/NullModel.h
+++ b/Processes/NullModel/NullModel.h
@@ -25,8 +25,8 @@ namespace corsika::process::null_model {
 
     void Init();
 
-    template <typename Particle, typename Track, typename Stack>
-    process::EProcessReturn DoContinuous(Particle&, Track&, Stack&) const;
+    template <typename Particle, typename Track>
+    process::EProcessReturn DoContinuous(Particle&, Track&) const;
 
     template <typename Particle, typename Track>
     corsika::units::si::LengthType MaxStepLength(Particle&, Track&) const;
diff --git a/Processes/NullModel/testNullModel.cc b/Processes/NullModel/testNullModel.cc
index ed639eca4cb54fa3f1f6a676a27c01eb37663b6c..4ab4c0422d5638703e5dff5d6e81f9eabaa14819 100644
--- a/Processes/NullModel/testNullModel.cc
+++ b/Processes/NullModel/testNullModel.cc
@@ -55,7 +55,7 @@ TEST_CASE("NullModel", "[processes]") {
 
     model.Init();
     [[maybe_unused]] const process::EProcessReturn ret =
-        model.DoContinuous(particle, track, stack);
+        model.DoContinuous(particle, track);
     LengthType const length = model.MaxStepLength(particle, track);
 
     CHECK((length / 10_m) == Approx(1));