diff --git a/regen/reentr.pl b/regen/reentr.pl
index 5742278fe99c..8ee209fb2453 100644
--- a/regen/reentr.pl
+++ b/regen/reentr.pl
@@ -705,6 +705,7 @@ sub define {
             }
 
             # This needs a special case, see its definition in config.h
+            # XXX
             my $setup = ($func eq 'localtime') ? "L_R_TZSET " : "";
 
             my $call = "$setup${func}_r($v$w)";