diff --git a/make-block.pl b/make-block.pl
index 425eafb..182050e 100755
--- a/make-block.pl
+++ b/make-block.pl
@@ -117,7 +117,7 @@ MAIN: {
         } @block_ip;
     } sort keys %domains;
 
-    printf STDERR "%d domains written to %s from\n", $written, $out;
+    printf STDERR "%d domains written to %s from\n", $written, $out // 'STDOUT';
     printf STDERR " - %d .domains files\n", (scalar @domain_lists);
     printf STDERR " - %d .hosts files\n", (scalar @hosts_lists);
     printf STDERR "(%d duplicates)\n", $dupes if $dupes;