diff --git a/AMDiS/src/DOFMatrix.cc b/AMDiS/src/DOFMatrix.cc
index 59b329d0a69fa61aab9778d8da33d81c7acb9e3a..ea4eeff6b89f5edec170082b01b145613b8c500e 100644
--- a/AMDiS/src/DOFMatrix.cc
+++ b/AMDiS/src/DOFMatrix.cc
@@ -685,6 +685,8 @@ namespace AMDiS {
 	matrix[*it][0].entry = 1.0;
       }
     }
+
+    rows->clear();
   }
 
   int DOFMatrix::getNumCols() const {