diff --git a/AMDiS/src/parallel/PetscSolverGlobalBlockMatrix.cc b/AMDiS/src/parallel/PetscSolverGlobalBlockMatrix.cc
index f7fd4b3a2e648da6c326b443c7bc722ad0b45bbc..3bdd3fc3cfa09e50fed970b3c0316f2302aec829 100644
--- a/AMDiS/src/parallel/PetscSolverGlobalBlockMatrix.cc
+++ b/AMDiS/src/parallel/PetscSolverGlobalBlockMatrix.cc
@@ -60,8 +60,8 @@ namespace AMDiS {
 	MatCreateAIJ(domainComm,
 		     nRankRows * blockSize[i], nRankRows * blockSize[j],
 		     nOverallRows * blockSize[i], nOverallRows * blockSize[j],
-		     30 * blockSize[i], PETSC_NULL, 
-		     30 * blockSize[j], PETSC_NULL,
+		     300 * blockSize[i], PETSC_NULL, 
+		     300 * blockSize[j], PETSC_NULL,
 		     &(nestMat[i * nBlocks + j]));
 			
     for (int i = 0; i < nComponents; i++)
@@ -260,8 +260,8 @@ namespace AMDiS {
 
     vector<int> cols;
     vector<double> values;
-    cols.reserve(300);
-    values.reserve(300);
+    cols.reserve(3000);
+    values.reserve(3000);
     
     // === Traverse all rows of the dof matrix and insert row wise the values ===
     // === to the PETSc matrix.                                               ===