diff --git a/Koha/REST/V1/Patrons.pm b/Koha/REST/V1/Patrons.pm
index 30548502a9..ea65155eb9 100644
--- a/Koha/REST/V1/Patrons.pm
+++ b/Koha/REST/V1/Patrons.pm
@@ -383,11 +383,11 @@ sub _to_model {
     }
 
     if ( exists $patron->{lastseen} ) {
-        $patron->{lastseen} = output_pref({ dt => dt_from_string( $patron->{lastseen} ), dateformat => 'sql' });
+        $patron->{lastseen} = output_pref({ str => $patron->{lastseen}, dateformat => 'sql' });
     }
 
     if ( exists $patron->{updated_on} ) {
-        $patron->{updated_on} = output_pref({ dt => dt_from_string( $patron->{updated_on} ), dateformat => 'sql' });
+        $patron->{updated_on} = output_pref({ str => $patron->{updated_on}, dateformat => 'sql' });
     }
 
     return $patron;