diff --git a/Koha/DateUtils.pm b/Koha/DateUtils.pm
index 2b8ee8b5a2..459a5a89d7 100644
--- a/Koha/DateUtils.pm
+++ b/Koha/DateUtils.pm
@@ -254,8 +254,13 @@ sub output_pref {
           : $dt->strftime("%Y-%m-%d $time");
     }
     elsif ( $pref =~ m/^rfc3339/ ) {
-        $date = $dt->strftime('%FT%T%z');
-        substr($date, -2, 0, ':'); # timezone "HHmm" => "HH:mm"
+        if (!$dateonly) {
+            $date = $dt->strftime('%FT%T%z');
+            substr($date, -2, 0, ':'); # timezone "HHmm" => "HH:mm"
+        }
+        else {
+            $date = $dt->strftime("%Y-%m-%d");
+        }
     }
     elsif ( $pref =~ m/^metric/ ) {
         $date = $dateonly