diff --git a/src/field/interpolators/NearestNeighborFieldInterpolator.h b/src/field/interpolators/NearestNeighborFieldInterpolator.h
index 975c55edb4c52d0ea197391a88b271588bbf7729..43279021302d6cac0a1bdd930eb0870d8fbfba6a 100644
--- a/src/field/interpolators/NearestNeighborFieldInterpolator.h
+++ b/src/field/interpolators/NearestNeighborFieldInterpolator.h
@@ -60,13 +60,13 @@ public:
    inline bool operator==( const OwnType & other ){ return baseField_ == other.baseField_; }
 
    template< typename ForwardIterator_T >
-   inline void get( const Vector3<real_t> & position, ForwardIterator_T interpolationResultBegin )
+   inline void get( const Vector3<real_t> & position, ForwardIterator_T interpolationResultBegin ) const
    {
       get( position[0], position[1], position[2], interpolationResultBegin );
    }
 
    template< typename ForwardIterator_T >
-   inline void get( const real_t & x, const real_t & y, const real_t & z, ForwardIterator_T interpolationResultBegin )
+   inline void get( const real_t & x, const real_t & y, const real_t & z, ForwardIterator_T interpolationResultBegin ) const
    {
 
       WALBERLA_ASSERT(block_.getAABB().contains(x,y,z),
diff --git a/src/field/interpolators/TrilinearFieldInterpolator.h b/src/field/interpolators/TrilinearFieldInterpolator.h
index bdac4ff1a6d752b6d5d898139de421fb5793f43b..ff9625644844f1a473a9fb7d18587cb956c696fe 100644
--- a/src/field/interpolators/TrilinearFieldInterpolator.h
+++ b/src/field/interpolators/TrilinearFieldInterpolator.h
@@ -62,16 +62,16 @@ public:
    }
 
 
-   inline bool operator==( const OwnType & other ){ return baseField_ == other.baseField_; }
+   inline bool operator==( const OwnType & other ) const { return baseField_ == other.baseField_; }
 
    template< typename ForwardIterator_T >
-   inline void get( const Vector3<real_t> & position, ForwardIterator_T interpolationResultBegin )
+   inline void get( const Vector3<real_t> & position, ForwardIterator_T interpolationResultBegin ) const
    {
       get( position[0], position[1], position[2], interpolationResultBegin );
    }
 
    template< typename ForwardIterator_T >
-   inline void get( const real_t & x, const real_t & y, const real_t & z, ForwardIterator_T interpolationResultBegin )
+   inline void get( const real_t & x, const real_t & y, const real_t & z, ForwardIterator_T interpolationResultBegin ) const
    {
       WALBERLA_ASSERT(block_.getAABB().contains(x,y,z),
                       "Interpolation position <" << x << ", " << y << ", " << z << "> is not contained inside the block of this interpolator with AABB " << block_.getAABB() << " !");
@@ -166,7 +166,7 @@ public:
 private:
 
    template< typename ForwardIterator_T >
-   void addWeightedCellValue( ForwardIterator_T interpolationResultBegin, const Cell & curCell, const real_t & weighting )
+   void addWeightedCellValue( ForwardIterator_T interpolationResultBegin, const Cell & curCell, const real_t & weighting ) const
    {
       for( uint_t f = uint_t(0); f < F_SIZE; ++f )
       {