diff --git a/src/neohookeassembler.cc b/src/neohookeassembler.cc
index 19dc254f94e32469a3c014add46372f213d8cb66..66852f439ab0a6ad9419aee54b9cca136a768655 100644
--- a/src/neohookeassembler.cc
+++ b/src/neohookeassembler.cc
@@ -254,8 +254,7 @@ getLocalMatrix( EntityType &entity,
 #else
                         // Fischer / Wriggers
                         C[i][j][k][l] = lambda_*(parJparU[i][j]*parJparU[k][l] + (J-1)*Elasticity::det_dudu_tmpl(parDerU,i,j,k,l));
-                        //C[i][j][k][l] += -(2*mu_)/J/J * (J*det_dudu_tmpl(parDerU,i,j,k,l) - parJparU[i][j]*parJparU[k][l]);
-                        C[i][j][k][l] += (2*mu_)*Gamma_xx(J)*det_dudu_tmpl(parDerU,i,j,k,l);
+                        C[i][j][k][l] += -(2*mu_)/J/J * (J*Elasticity::det_dudu_tmpl(parDerU,i,j,k,l) - parJparU[i][j]*parJparU[k][l]);
                         C[i][j][k][l] += mu_ * tr_E_dudu;
 #endif
                     }
@@ -292,7 +291,7 @@ getLocalMatrix( EntityType &entity,
 #else
                 // Fischer
                 fu[i][j]  = lambda_ * (J-1) * parJparU[i][j];
-                fu[i][j] += 2* mu_ *Gamma_x(J) * parJparU[i][j];
+                fu[i][j] -= 2* mu_ /J * parJparU[i][j];
                 fu[i][j] += mu_ * trE_du[i][j];
 #endif
             }
@@ -469,7 +468,7 @@ computeEnergy(const BlockVector<FieldVector<double, dim> >& sol) const
             energy += weight * (lambda_ * (J*J-1)/4 - (lambda_/2 + mu_ ) * std::log(J) + mu_*trE);
 #else
             // Fischer
-            energy += weight * (lambda_ * (J-1)*(J-1)/2 + 2*mu_ * Gamma(J) + mu_*trE);
+            energy += weight * (lambda_ * (J-1)*(J-1)/2 - 2*mu_ * std::log(J) + mu_*trE);
 #endif
         }