diff --git a/MaterialLib/FractureModels/MohrCoulomb.cpp b/MaterialLib/FractureModels/MohrCoulomb.cpp
index 15bd88909b0693a778fa9c05a8c8290bbfd16a41..54932246c4d6a1ff3db7a4a8d99e37e31a239566 100644
--- a/MaterialLib/FractureModels/MohrCoulomb.cpp
+++ b/MaterialLib/FractureModels/MohrCoulomb.cpp
@@ -101,10 +101,10 @@ void MohrCoulomb<DisplacementDim>::computeConstitutiveRelation(
     }
     else
     {
-        for (int i=0; i<index_ns-1; i++)
+        for (int i=0; i<index_ns; i++)
             dFs_dS[i] = boost::math::sign(tau) / tau * sigma[i];
 
-        for (int i=0; i<index_ns-1; i++)
+        for (int i=0; i<index_ns; i++)
             dQs_dS[i] = boost::math::sign(tau) / tau * sigma[i];
     }
     dFs_dS[index_ns] = std::tan(mat.phi);