diff --git a/reviews/reviewswaiting.pl b/reviews/reviewswaiting.pl
index de076a6782..9526a4c820 100755
--- a/reviews/reviewswaiting.pl
+++ b/reviews/reviewswaiting.pl
@@ -16,6 +16,8 @@
 # Suite 330, Boston, MA  02111-1307 USA
 
 use strict;
+use warnings;
+
 use CGI;
 use C4::Auth;
 use C4::Output;
@@ -36,7 +38,7 @@ my ( $template, $loggedinuser, $cookie ) = get_template_and_user(
     }
 );
 
-my $op       = $query->param('op');
+my $op       = $query->param('op') || '';
 my $reviewid = $query->param('reviewid');
 
 if ( $op eq 'approve' ) {