diff --git a/build/addresses.pl b/build/addresses.pl
index f2bfbbdc..e992a1ed 100755
--- a/build/addresses.pl
+++ b/build/addresses.pl
@@ -15,9 +15,13 @@
 #
 # Load extra addresses.
 #
+# One extra address per line.  Blank lines and lines starting with '#' are
+# ignored.
+#
 open(EXTRAS, "extra_addresses.txt") || die "could not open extra addresses file";
 while (<EXTRAS>) {
 	chomp;	# remove \n
+	next if /^#/;
 	$extras{$_} = 1 unless $_ eq '';
 }
 close EXTRAS;