diff --git a/src/pde/boundary/Neumann.h b/src/pde/boundary/Neumann.h
index 198b708ce51cc2dc1e284e20ba518a86bd11411e..ba5fb0e8c7e09ee039a793aee5f1623a10053250 100644
--- a/src/pde/boundary/Neumann.h
+++ b/src/pde/boundary/Neumann.h
@@ -353,7 +353,7 @@ inline Neumann< Stencil_T, flag_t >::Neumann( const BoundaryUID & boundaryUID, c
    neumannBC_ = make_shared< Field_T >( rhsField_->xSize(), rhsField_->ySize(), rhsField_->zSize(), uint_t(1), field::zyxf );
 
    for(auto d = Stencil_T::beginNoCenter(); d != Stencil_T::end(); ++d ){
-      dx_[d.toIdx()] = Vector3<real_t>(stencil::cx[d.toIdx()]*blocks.dx(), stencil::cy[d.toIdx()]*blocks.dy(), stencil::cz[d.toIdx()]*blocks.dz() ).sqrLength();
+      dx_[d.toIdx()] = Vector3<real_t>(real_c(stencil::cx[d.toIdx()])*blocks.dx(), real_c(stencil::cy[d.toIdx()])*blocks.dy(), real_c(stencil::cz[d.toIdx()])*blocks.dz() ).sqrLength();
       // WALBERLA_LOG_DEVEL("dx in direction " << d.dirString() << ":" << dx_[d.toIdx()]);
    }
 
diff --git a/tests/pde/BoundaryTest.cpp b/tests/pde/BoundaryTest.cpp
index 1164c586c40a953b2063cfaaaa1c03b995978f79..ab22a765f1dc1de37b6b9880505ce0b4ee172bb3 100644
--- a/tests/pde/BoundaryTest.cpp
+++ b/tests/pde/BoundaryTest.cpp
@@ -346,11 +346,11 @@ int main( int argc, char** argv )
    if( !shortrun )
    {
       Cell cellNearBdry( 75, 2, 0 );
-      real_t solNearBdry( -0.16347 );
+      real_t solNearBdry( real_c(-0.16347) );
       Cell cellNearBdryLrg( 24, 95, 0 );
-      real_t solNearBdryLrg( 201.47 );
+      real_t solNearBdryLrg( real_c(201.47) );
       Cell cellDomCentr( 100, 50, 0 );
-      real_t solDomCentr( 0.37587 );
+      real_t solDomCentr( real_c(0.37587) );
 
       for( auto block = blocks->begin(); block != blocks->end(); ++block )
       {
@@ -378,11 +378,11 @@ int main( int argc, char** argv )
    else
    {
       Cell cellNearBdry( 75, 2, 0 );
-      real_t solNearBdry( -0.008355 );
+      real_t solNearBdry( real_c(-0.008355) );
       Cell cellNearBdryLrg( 24, 95, 0 );
-      real_t solNearBdryLrg( 132.188 );
+      real_t solNearBdryLrg( real_c(132.188) );
       Cell cellDomCentr( 100, 50, 0 );
-      real_t solDomCentr( 0.017603 );
+      real_t solDomCentr( 0.017603f );
 
       for( auto block = blocks->begin(); block != blocks->end(); ++block )
       {