--- /usr/share/fai/setup-storage/Commands.pm    2019-03-22 16:11:35.975710699 +0100
+++ /usr/share/fai/setup-storage/Commands.pm    2019-03-22 16:12:58.343714173 +0100
@@ -881,7 +881,7 @@
     # prevent error due to different VG name of existing VG
     if (defined($FAI::configs{$d})) {
       # don't deactivate preserved VGs to prevent blkid error later on
-      foreach my $v (keys %{ $FAI::configs->{$d}->{volumes} }) {
+      foreach my $v (keys %{ $FAI::configs{$d}->{volumes} }) {
         $preserved = 1 if ($FAI::configs{$d}{volumes}{$v}{size}{preserve});
       }
     }

EOM