diff --git a/Core/Computation/SpecularComputation.cpp b/Core/Computation/SpecularComputation.cpp
index 65f2f17d2fa7ea14522cefcd2d4931796b670acd..b1d8f6147aef9682076c74e3f2fdfd29efb92832 100644
--- a/Core/Computation/SpecularComputation.cpp
+++ b/Core/Computation/SpecularComputation.cpp
@@ -34,14 +34,14 @@ SpecularComputation::~SpecularComputation() = default;
 void SpecularComputation::runProtected()
 {
     const SliceStack& slices = m_re_sample.averageSlices();
-    const RoughnessModel& r_model = m_re_sample.sample().roughnessModel();
+
     for (auto it = m_begin_it; it != m_end_it; ++it) {
         SpecularElement& ele = *it;
         if (!ele.isCalculated())
             continue;
         if (m_re_sample.polarizing()) {
             const Eigen::Matrix2cd R =
-                Compute::SpecularMagnetic::topLayerR(slices, ele.produceKz(slices), r_model, true);
+                Compute::SpecularMagnetic::topLayerR(slices, ele.produceKz(slices), true);
 
             const auto& polarization = ele.polarizationHandler().getPolarization();
             const auto& analyzer = ele.polarizationHandler().getAnalyzerOperator();
@@ -52,7 +52,7 @@ void SpecularComputation::runProtected()
 
         } else {
             const complex_t R =
-                Compute::SpecularScalar::topLayerR(slices, ele.produceKz(slices), r_model);
+                Compute::SpecularScalar::topLayerR(slices, ele.produceKz(slices));
             ele.setIntensity(std::norm(R));
         }
 
diff --git a/Resample/Specular/ComputeFluxMagnetic.cpp b/Resample/Specular/ComputeFluxMagnetic.cpp
index b322be311cdd042530b839fa5487c8993b5672f0..9d893157ef8238130dc209c6191a1778c7f1673e 100644
--- a/Resample/Specular/ComputeFluxMagnetic.cpp
+++ b/Resample/Specular/ComputeFluxMagnetic.cpp
@@ -186,12 +186,12 @@ Fluxes Compute::SpecularMagnetic::fluxes(const SliceStack& slices, const kvector
 
 Eigen::Matrix2cd Compute::SpecularMagnetic::topLayerR(const SliceStack& slices,
                                                       const std::vector<complex_t>& kzs,
-                                                      const RoughnessModel& r_model, bool forward)
+                                                      bool forward)
 {
-    ASSERT(slices.size() == kzs.size());
+    const RoughnessModel& r_model = slices.roughnessModel();
 
+    ASSERT(slices.size() == kzs.size());
     const auto N = slices.size();
-
     if (N == 1)
         return Eigen::Matrix2cd::Zero();
     else if (kzs[0] == 0.)
diff --git a/Resample/Specular/ComputeFluxMagnetic.h b/Resample/Specular/ComputeFluxMagnetic.h
index 9a927813b97e1f64f3f11f5aa9f1ab04bf7ef216..e15370ff177ac3467bde401f6d423a304a5f3a43 100644
--- a/Resample/Specular/ComputeFluxMagnetic.h
+++ b/Resample/Specular/ComputeFluxMagnetic.h
@@ -46,7 +46,7 @@ Fluxes fluxes(const SliceStack& slices, const kvector_t& k, bool forward);
 //! Computes the Fresnel R coefficient for the top layer only
 //! Introduced in order to speed up pure reflectivity computations
 Eigen::Matrix2cd topLayerR(const SliceStack& slices, const std::vector<complex_t>& kzs,
-                           const RoughnessModel&, bool forward);
+                           bool forward);
 } // namespace Compute::SpecularMagnetic
 
 #endif // BORNAGAIN_RESAMPLE_SPECULAR_COMPUTEFLUXMAGNETIC_H
diff --git a/Resample/Specular/ComputeFluxScalar.cpp b/Resample/Specular/ComputeFluxScalar.cpp
index 13b97f6389a5d6bdea3d5e6303340a991718914a..e661ff34826791e1b6809d51a53f193ecfb6bf21 100644
--- a/Resample/Specular/ComputeFluxScalar.cpp
+++ b/Resample/Specular/ComputeFluxScalar.cpp
@@ -135,13 +135,12 @@ Fluxes Compute::SpecularScalar::fluxes(const SliceStack& slices, const kvector_t
 }
 
 complex_t Compute::SpecularScalar::topLayerR(const SliceStack& slices,
-                                             const std::vector<complex_t>& kz,
-                                             const RoughnessModel& r_model)
+                                             const std::vector<complex_t>& kz)
 {
-    ASSERT(slices.size() == kz.size());
+    const RoughnessModel& r_model = slices.roughnessModel();
 
+    ASSERT(slices.size() == kz.size());
     const size_t N = slices.size();
-
     if (N == 1)
         return 0.; // only one layer present, there's nothing left to calculate
     if (kz[0] == 0.)
diff --git a/Resample/Specular/ComputeFluxScalar.h b/Resample/Specular/ComputeFluxScalar.h
index 5fd2459e0b67a7385a40413c40b2e811489ec047..8121023b4a46a919bf013bdb000cc338cfc53b55 100644
--- a/Resample/Specular/ComputeFluxScalar.h
+++ b/Resample/Specular/ComputeFluxScalar.h
@@ -39,8 +39,7 @@ Fluxes fluxes(const SliceStack& slices, const kvector_t& k);
 
 //! Computes the Fresnel R coefficient for the top layer only.
 //! Introduced in order to speed up pure reflectivity computations.
-complex_t topLayerR(const SliceStack& slices, const std::vector<complex_t>& kz,
-                    const RoughnessModel& r_model);
+complex_t topLayerR(const SliceStack& slices, const std::vector<complex_t>& kz);
 
 } // namespace Compute::SpecularScalar
 
diff --git a/auto/Wrap/doxygenResample.i b/auto/Wrap/doxygenResample.i
index 50ff27377c58731ba3021d50315c8416153c0277..67def255217a3f086a9f9c92094ec54b080eaa68 100644
--- a/auto/Wrap/doxygenResample.i
+++ b/auto/Wrap/doxygenResample.i
@@ -787,7 +787,7 @@ Calculate z-admixtures occupied by particles.
 Computes refraction angle reflection/transmission coefficients for given sliced multilayer and wavevector k 
 ";
 
-%feature("docstring")  Compute::SpecularMagnetic::topLayerR "Eigen::Matrix2cd Compute::SpecularMagnetic::topLayerR(const SliceStack &slices, const std::vector< complex_t > &kzs, const RoughnessModel &, bool forward)
+%feature("docstring")  Compute::SpecularMagnetic::topLayerR "Eigen::Matrix2cd Compute::SpecularMagnetic::topLayerR(const SliceStack &slices, const std::vector< complex_t > &kzs, bool forward)
 
 Computes the Fresnel R coefficient for the top layer only Introduced in order to speed up pure reflectivity computations 
 ";
@@ -799,7 +799,7 @@ Computes the Fresnel R coefficient for the top layer only Introduced in order to
 Computes refraction angles and transmission/reflection coefficients for given coherent wave propagation in a multilayer. 
 ";
 
-%feature("docstring")  Compute::SpecularScalar::topLayerR "complex_t Compute::SpecularScalar::topLayerR(const SliceStack &slices, const std::vector< complex_t > &kz, const RoughnessModel &r_model)
+%feature("docstring")  Compute::SpecularScalar::topLayerR "complex_t Compute::SpecularScalar::topLayerR(const SliceStack &slices, const std::vector< complex_t > &kz)
 
 Computes the Fresnel R coefficient for the top layer only. Introduced in order to speed up pure reflectivity computations. 
 ";