diff --git a/lib/Wiki/Toolkit/Store/Database.pm b/lib/Wiki/Toolkit/Store/Database.pm
index 92f79a3..c259a3d 100644
--- a/lib/Wiki/Toolkit/Store/Database.pm
+++ b/lib/Wiki/Toolkit/Store/Database.pm
@@ -1739,7 +1739,7 @@ sub list_nodes_by_missing_metadata {
     my $dbh = $self->dbh;
     if ( $args{ignore_case} ) {
         $type  = lc( $type  );
-        $value = lc( $value );
+        $value = lc( $value || "");
     }
 
     my @nodes;