diff --git a/lib/DoctorKarma/Model/User.pm b/lib/DoctorKarma/Model/User.pm
index d80d144..91c2360 100644
--- a/lib/DoctorKarma/Model/User.pm
+++ b/lib/DoctorKarma/Model/User.pm
@@ -37,7 +37,7 @@ sub can_modify_karma {
         return 1;
     }
     return DateTime->now >
-      $self->last_karma_given_date->clone->add( minutes => 1 );
+      $self->last_karma_given_date->add( minutes => 1 );
 }
 
 sub first_name {
@@ -81,7 +81,10 @@ sub id_user {
         if ( defined $last_karma_given_date ) {
             $self->{last_karma_given_date} = $last_karma_given_date;
         }
-        return $self->{last_karma_given_date}->clone;
+        if ( defined $self->{last_karma_given_date} ) {
+            return $self->{last_karma_given_date}->clone;
+        }
+        return undef;
     }
 }