diff --git a/opac/opac-export.pl b/opac/opac-export.pl
index e8f7ededc6..d24ddb2b1b 100755
--- a/opac/opac-export.pl
+++ b/opac/opac-export.pl
@@ -18,7 +18,6 @@
 # Suite 330, Boston, MA  02111-1307 USA
 #
 
-
 use strict;
 use warnings;
 
@@ -31,59 +30,57 @@ use C4::Auth;
 use C4::Ris;
 
 my $query = new CGI;
-my $op=$query->param("op");
-my $format=$query->param("format");
-if ($op eq "export") {
-	my $biblionumber = $query->param("bib");
-	my $error;
+my $op=$query->param("op")||''; #op=export is currently the only use
+my $format=$query->param("format")||'utf8';
+my $biblionumber = $query->param("bib")||0;
+my ($marc, $error)= ('','');
 
-		if ($biblionumber){
-
-			my $marc = GetMarcBiblio($biblionumber, 1);
-
-			if ($format =~ /endnote/) {
-				$marc = marc2endnote($marc);
-				$format = 'endnote';
-			}
-			elsif ($format =~ /marcxml/) {
-				$marc = marc2marcxml($marc);
-			}
-			elsif ($format=~ /mods/) {
-				$marc = marc2modsxml($marc);
-			}
- 			elsif ($format =~ /ris/) {
- 				$marc = marc2ris(MARC::Record->new_from_usmarc($marc));
- 			}
-			elsif ($format =~ /bibtex/) {
-				$marc = marc2bibtex(C4::Biblio::GetMarcBiblio($biblionumber),$biblionumber);
-			}
-			elsif ($format =~ /dc/) {
-				($error,$marc) = marc2dcxml($marc,1);
-				$format = "dublin-core.xml";
-			}
-			elsif ($format =~ /marc8/) {
-				($error,$marc) = changeEncoding($marc,"MARC","MARC21","MARC-8");
-				if (! $error){
-				    $marc = $marc->as_usmarc();
-				}
-			}
-			elsif ($format =~ /utf8/) {
-				C4::Charset::SetUTF8Flag($marc,1);
-				$marc = $marc->as_usmarc();
-			}
-
-		if ($error){
-		    print $query->header();
-		    print $query->start_html();
-		    print "<h1>An error occured </h1>";
-		    print $error;
-		    print $query->end_html();
-		}
-		else {
-		    print $query->header(
-				    -type => 'application/octet-stream',
-		    -attachment=>"bib-$biblionumber.$format");
-		    print $marc;
-		}
-	    }
+$marc = GetMarcBiblio($biblionumber, 1) if $biblionumber;
+if(!$marc) {
+    print $query->redirect("/cgi-bin/koha/errors/404.pl");
+    exit;
+}
+elsif ($format =~ /endnote/) {
+    $marc = marc2endnote($marc);
+}
+elsif ($format =~ /marcxml/) {
+    $marc = marc2marcxml($marc);
+}
+elsif ($format=~ /mods/) {
+    $marc = marc2modsxml($marc);
+}
+elsif ($format =~ /ris/) {
+    $marc = marc2ris(MARC::Record->new_from_usmarc($marc));
+}
+elsif ($format =~ /bibtex/) {
+    $marc = marc2bibtex(C4::Biblio::GetMarcBiblio($biblionumber),$biblionumber);
+}
+elsif ($format =~ /dc/) {
+    ($error,$marc) = marc2dcxml($marc,1);
+    $format = "dublin-core.xml";
+}
+elsif ($format =~ /marc8/) {
+    ($error,$marc) = changeEncoding($marc,"MARC","MARC21","MARC-8");
+    $marc = $marc->as_usmarc() unless $error;
+}
+elsif ($format =~ /utf8/) {
+    C4::Charset::SetUTF8Flag($marc,1);
+    $marc = $marc->as_usmarc();
+}
+else {
+    $error= "Format $format is not supported.";
+}
+
+if ($error){
+    print $query->header();
+    print $query->start_html();
+    print "<h1>An error occurred </h1>";
+    print $error;
+    print $query->end_html();
+}
+else {
+    print $query->header(
+      -type => 'application/octet-stream',
+      -attachment=>"bib-$biblionumber.$format");
+    print $marc;
 }