diff --git a/AMDiS/src/parallel/PetscSolverFeti.cc b/AMDiS/src/parallel/PetscSolverFeti.cc
index 1edcf370fb0543acccbae3a276fb6e599c3fc055..7f50efae7020d42c794ba0a00bea0dbb690d1c7c 100644
--- a/AMDiS/src/parallel/PetscSolverFeti.cc
+++ b/AMDiS/src/parallel/PetscSolverFeti.cc
@@ -1825,7 +1825,9 @@ namespace AMDiS { namespace Parallel {
     MatNullSpaceCreate(domainComm, PETSC_FALSE, 1, &nullSpaceBasis, 
 		       &matNullSpace);
     MatSetNullSpace(mat_feti, matNullSpace);
-    KSPSetNullSpace(ksp_feti, matNullSpace);
+    Mat amat, pmat;
+    KSPGetOperators(ksp, &amat, &pmat);
+    MatSetNullSpace(amat, matNullSpace);
     MatNullSpaceDestroy(&matNullSpace);
 
     VecDestroy(&ktest0);
diff --git a/AMDiS/src/parallel/PetscSolverGlobalMatrix.cc b/AMDiS/src/parallel/PetscSolverGlobalMatrix.cc
index 6a85d7309ed5da4f836cbde7f9fa544ff64472b0..f43daef8f34b937e735bc3732e9763103889ab36 100644
--- a/AMDiS/src/parallel/PetscSolverGlobalMatrix.cc
+++ b/AMDiS/src/parallel/PetscSolverGlobalMatrix.cc
@@ -951,7 +951,10 @@ namespace AMDiS { namespace Parallel {
     
     MatNullSpace matNullSpace;
     MatNullSpaceCreate(domainComm, PETSC_FALSE, 1, &nullSpaceBasis, &matNullSpace);
-    KSPSetNullSpace(ksp, matNullSpace);
+
+    Mat amat, pmat;
+    KSPGetOperators(ksp, &amat, &pmat);
+    MatSetNullSpace(amat, matNullSpace);
     MatNullSpaceDestroy(&matNullSpace);
 
     VecDestroy(&nullSpaceBasis);
@@ -962,7 +965,9 @@ namespace AMDiS { namespace Parallel {
   {
     MatNullSpace matNullSpace;
     MatNullSpaceCreate(domainComm, PETSC_TRUE, 0, PETSC_NULL, &matNullSpace);
-    KSPSetNullSpace(ksp, matNullSpace);
+    Mat amat, pmat;
+    KSPGetOperators(ksp, &amat, &pmat);                             
+    MatSetNullSpace(amat, matNullSpace);
     MatNullSpaceDestroy(&matNullSpace);
   }