diff --git a/catalogue/MARCdetail.pl b/catalogue/MARCdetail.pl
index bcb6f5e972..e630d18344 100755
--- a/catalogue/MARCdetail.pl
+++ b/catalogue/MARCdetail.pl
@@ -200,9 +200,8 @@ for ( my $tabloop = 0 ; $tabloop <= 10 ; $tabloop++ ) {
                 {
                     $subfield_data{marc_value} = $subf[$i][1];
 					$subfield_data{is_url} = 1;
-                }
-                elsif ( $tagslib->{ $fields[$x_i]->tag() }->{ $subf[$i][0] }
-                    ->{kohafield} eq "biblioitems.isbn" )
+                } elsif ( $tagslib->{ $fields[$x_i]->tag() }->{ $subf[$i][0] }->{kohafield}
+                    && $tagslib->{ $fields[$x_i]->tag() }->{ $subf[$i][0] }->{kohafield} eq "biblioitems.isbn" )
                 {
 
 #                    warn " tag : ".$tagslib->{$fields[$x_i]->tag()}." subfield :".$tagslib->{$fields[$x_i]->tag()}->{$subf[$i][0]}. "ISBN : ".$subf[$i][1]."PosttraitementISBN :".DisplayISBN($subf[$i][1]);