diff --git a/common/fmatrix.hh b/common/fmatrix.hh
index 4b0b980e1dc9157a5de7d0a2471d8800e384dfad..3b335819e6eedd6df5f085199b66174d2260a1cb 100644
--- a/common/fmatrix.hh
+++ b/common/fmatrix.hh
@@ -704,7 +704,7 @@ namespace Dune {
       }
 
       // U A^{-1} = Y
-      for (size_type i=n-1; i>=0; i--) {
+      for (size_type i=n-1; i!=0; i--) {
         for (size_type k=0; k<n; k++) {
           for (size_type j=i+1; j<n; j++)
             p[i][k] -= U[i][j]*p[j][k];
@@ -712,7 +712,7 @@ namespace Dune {
         }
       }
 
-      for(size_type i=n-1; i>=0; --i) {
+      for(size_type i=n-1; i!=0; --i) {
         if(i!=pivot[i])
           for(size_type j=0; j<n; ++j)
             std::swap(p[j][pivot[i]], p[j][i]);