diff --git a/Sample/RT/MatrixRTCoefficients.h b/Sample/RT/MatrixRTCoefficients.h
index a7c3858ebb987d3b07599dffdef6424da5b44325..0f467eda100970224f81c3a690803f87f488ee78 100644
--- a/Sample/RT/MatrixRTCoefficients.h
+++ b/Sample/RT/MatrixRTCoefficients.h
@@ -27,7 +27,6 @@ class MatrixRTCoefficients : public ILayerRTCoefficients {
 public:
     friend class SpecularMagneticStrategy;
     friend class SpecularMagneticNCStrategy;
-    friend class SpecularMagneticNCTestingStrategy;
     friend class SpecularMagneticTanhStrategy;
 
     MatrixRTCoefficients(double kz_sign, Eigen::Vector2cd eigenvalues, kvector_t b,