diff --git a/site-generator b/site-generator
index f0fc16f..562b6a6 100755
--- a/site-generator
+++ b/site-generator
@@ -266,7 +266,7 @@ sub get_filename {
 		else {
 			$filename = $$config{'filename'};
 			my $padded_index = "";
-			if ($$config{'id'}) {
+			if (exists $$config{'id'}) {
 				$padded_index = sprintf("%04d", $$config{'id'});
 			}
 			$filename =~ s/\[id\]/$padded_index/;