diff --git a/test/multidomain/embedded/1d3d/root_soil_benchmark/problem_root.hh b/test/multidomain/embedded/1d3d/root_soil_benchmark/problem_root.hh
index b98842ba7616e5c9e508ef6a5076ec39507619a9..246d353ae54447718b748b3c8030dd04d8bc5115 100644
--- a/test/multidomain/embedded/1d3d/root_soil_benchmark/problem_root.hh
+++ b/test/multidomain/embedded/1d3d/root_soil_benchmark/problem_root.hh
@@ -12,6 +12,7 @@
 #ifndef DUMUX_TEST_ROOT_SOIL_BENCHMARK_ROOT_PROBLEM_HH
 #define DUMUX_TEST_ROOT_SOIL_BENCHMARK_ROOT_PROBLEM_HH
 
+#include <dumux/common/math.hh>
 #include <dumux/common/parameters.hh>
 #include <dumux/common/properties.hh>
 #include <dumux/common/boundarytypes.hh>
@@ -125,14 +126,6 @@ public:
         return values;
     }
 
-    //! Smooth minimum function
-    Scalar smoothMin(const Scalar a, const Scalar b, const Scalar k) const
-    {
-        using std::max; using std::min; using std::abs;
-        const auto h = max(k-abs(a-b), 0.0 )/k;
-        return min(a, b) - h*h*h*k*(1.0/6.0);
-    }
-
     //! Compute potential transpiration rate in kg/s
     Scalar potentialTranspirationRate() const
     {