diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/members/mancredit.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/members/mancredit.tt
index 057c3f6e81..4370a043ed 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/members/mancredit.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/members/mancredit.tt
@@ -66,6 +66,7 @@
                 <div class="tab-content">
                     <div role="tabpanel" class="tab-pane active">
                         <form action="/cgi-bin/koha/members/mancredit.pl" method="post" id="mancredit">
+                            <input type="hidden" name="op" value="cud-add" />
                             <input type="hidden" name="borrowernumber" id="borrowernumber" value="[% patron.borrowernumber | html %]" />
                             [% INCLUDE 'csrf-token.inc' %]
 
diff --git a/members/mancredit.pl b/members/mancredit.pl
index d91c9ef912..f58dbc1585 100755
--- a/members/mancredit.pl
+++ b/members/mancredit.pl
@@ -66,8 +66,8 @@ output_and_exit_if_error(
 my $library_id =
   C4::Context->userenv ? C4::Context->userenv->{'branch'} : undef;
 
-my $add = $input->param('cud-add');
-if ($add) {
+my $op = $input->param('op') // q{};
+if ( $op eq 'cud-add' ) {
 
 # Note: If the logged in user is not allowed to see this patron an invoice can be forced
 # Here we are trusting librarians not to hack the system