diff --git a/opm/autodiff/FullyImplicitBlackoilSolver.cpp b/opm/autodiff/FullyImplicitBlackoilSolver.cpp
index 645c58ab3..5ed92b4d6 100644
--- a/opm/autodiff/FullyImplicitBlackoilSolver.cpp
+++ b/opm/autodiff/FullyImplicitBlackoilSolver.cpp
@@ -1008,11 +1008,8 @@ namespace Opm {
 
         // compute gravity potensial using the face average as in eclipse and MRST
         const ADB rhoavg = ops_.caver * rho;
-        const V vz = geo_.z();
-        std::vector<int> blocksizes = rhoavg.blockPattern();
-        ADB z = ADB::constant(vz,blocksizes);
 
-        const ADB dp = ops_.ngrad * state.pressure - geo_.gravity()[2] * (rhoavg * (ops_.ngrad * z));
+        const ADB dp = ops_.ngrad * state.pressure - geo_.gravity()[2] * (rhoavg * (ops_.ngrad * geo_.z().matrix()));
 
         head = transi*dp;
         //head      = transi*(ops_.ngrad * state.pressure) + gflux;
diff --git a/opm/autodiff/GeoProps.hpp b/opm/autodiff/GeoProps.hpp
index db48a23a9..36c4241d4 100644
--- a/opm/autodiff/GeoProps.hpp
+++ b/opm/autodiff/GeoProps.hpp
@@ -84,11 +84,11 @@ namespace Opm
             }
         }
 
-        const Vector& poreVolume()       const { return pvol_ ; }
-        const Vector& transmissibility() const { return trans_; }
-        const Vector& gravityPotential() const { return gpot_ ; }
-        const Vector& z()                const  {return z_;}
-        const double* gravity()          const { return gravity_; }
+        const Vector& poreVolume()       const { return pvol_   ;}
+        const Vector& transmissibility() const { return trans_  ;}
+        const Vector& gravityPotential() const { return gpot_   ;}
+        const Vector& z()                const { return z_      ;}
+        const double* gravity()          const { return gravity_;}
 
     private:
         Vector pvol_ ;