diff --git a/dune/common/densematrix.hh b/dune/common/densematrix.hh
index 30970dba6580bd488addb2ce0dd225202d4061a7..f1ede4374f03b64134326f821eaa08c90fdf1781 100644
--- a/dune/common/densematrix.hh
+++ b/dune/common/densematrix.hh
@@ -811,7 +811,7 @@ namespace Dune
       luDecomposition(A, elim);
 
       // backsolve
-      for(size_type i=rows()-1; i>=0; i--) {
+      for(int i=rows()-1; i>=0; i--) {
         for (size_type j=i+1; j<rows(); j++)
           rhs[i] -= A[i][j]*x[j];
         x[i] = rhs[i]/A[i][i];