diff --git a/opm/core/utility/miscUtilities.cpp b/opm/core/utility/miscUtilities.cpp
index d2276689f..b84f94e6c 100644
--- a/opm/core/utility/miscUtilities.cpp
+++ b/opm/core/utility/miscUtilities.cpp
@@ -35,17 +35,15 @@ namespace Opm
 
     /// @brief Computes pore volume of all cells in a grid.
     /// @param[in]  grid      a grid
-    /// @param[in]  props     rock and fluid properties
+    /// @param[in]  porosity  array of grid.number_of_cells porosity values
     /// @param[out] porevol   the pore volume by cell.
     void computePorevolume(const UnstructuredGrid& grid,
-			   const Opm::IncompPropertiesInterface& props,
+                           const double* porosity,
 			   std::vector<double>& porevol)
     {
 	int num_cells = grid.number_of_cells;
-	ASSERT(num_cells == props.numCells());
 	porevol.resize(num_cells);
-	const double* poro = props.porosity();
-	std::transform(poro, poro + num_cells,
+	std::transform(porosity, porosity + num_cells,
 		       grid.cell_volumes,
 		       porevol.begin(),
 		       std::multiplies<double>());
@@ -54,22 +52,20 @@ namespace Opm
 
     /// @brief Computes pore volume of all cells in a grid, with rock compressibility effects.
     /// @param[in]  grid      a grid
-    /// @param[in]  props     rock and fluid properties
+    /// @param[in]  porosity  array of grid.number_of_cells porosity values
     /// @param[in]  rock_comp rock compressibility properties
     /// @param[in]  pressure  pressure by cell
     /// @param[out] porevol   the pore volume by cell.
     void computePorevolume(const UnstructuredGrid& grid,
-                           const IncompPropertiesInterface& props,
+                           const double* porosity,
                            const RockCompressibility& rock_comp,
                            const std::vector<double>& pressure,
                            std::vector<double>& porevol)
     {
         int num_cells = grid.number_of_cells;
-        ASSERT(num_cells == props.numCells());
         porevol.resize(num_cells);
-        const double* poro = props.porosity();
         for (int i = 0; i < num_cells; ++i) {
-            porevol[i] = poro[i]*grid.cell_volumes[i]*rock_comp.poroMult(pressure[i]);
+            porevol[i] = porosity[i]*grid.cell_volumes[i]*rock_comp.poroMult(pressure[i]);
         }
     }
 
diff --git a/opm/core/utility/miscUtilities.hpp b/opm/core/utility/miscUtilities.hpp
index 131580a69..40fe0059b 100644
--- a/opm/core/utility/miscUtilities.hpp
+++ b/opm/core/utility/miscUtilities.hpp
@@ -34,21 +34,21 @@ namespace Opm
 
     /// @brief Computes pore volume of all cells in a grid.
     /// @param[in]  grid      a grid
-    /// @param[in]  props     rock and fluid properties
+    /// @param[in]  porosity  array of grid.number_of_cells porosity values
     /// @param[out] porevol   the pore volume by cell.
     void computePorevolume(const UnstructuredGrid& grid,
-			   const Opm::IncompPropertiesInterface& props,
+                           const double* porosity,
 			   std::vector<double>& porevol);
 
 
     /// @brief Computes pore volume of all cells in a grid, with rock compressibility effects.
     /// @param[in]  grid      a grid
-    /// @param[in]  props     rock and fluid properties
+    /// @param[in]  porosity  array of grid.number_of_cells porosity values
     /// @param[in]  rock_comp rock compressibility properties
     /// @param[in]  pressure  pressure by cell
     /// @param[out] porevol   the pore volume by cell.
     void computePorevolume(const UnstructuredGrid& grid,
-                           const IncompPropertiesInterface& props,
+                           const double* porosity,
                            const RockCompressibility& rock_comp,
                            const std::vector<double>& pressure,
                            std::vector<double>& porevol);