diff --git a/Koha/DateUtils.pm b/Koha/DateUtils.pm
index a1fd088fe4..d7892dd4b1 100644
--- a/Koha/DateUtils.pm
+++ b/Koha/DateUtils.pm
@@ -94,7 +94,8 @@ s/(\d{4})(\d{2})(\d{2})\s+(\d{2})(\d{2})(\d{2})/$1-$2-$3T$4:$5:$6/;
 
 $date_string = output_pref($dt, [$format] );
 
-Returns a string containing the time & date formatted as per the C4::Context setting
+Returns a string containing the time & date formatted as per the C4::Context setting,
+or C<undef> if C<undef> was provided.
 
 A second parameter allows overriding of the syspref value. This is for testing only
 In usage use the DateTime objects own methods for non standard formatting
@@ -104,6 +105,9 @@ In usage use the DateTime objects own methods for non standard formatting
 sub output_pref {
     my $dt         = shift;
     my $force_pref = shift;    # if testing we want to override Context
+
+    return unless defined $dt;
+
     my $pref =
       defined $force_pref ? $force_pref : C4::Context->preference('dateformat');
     given ($pref) {