diff --git a/Makefile.PL b/Makefile.PL
index fc88314..3821b0d 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -18,11 +18,11 @@ WriteMakefile(
         'IO::Socket::SSL' => 0,
 # modules for specific features
         'Mail::DKIM'         => 0,
-        'File::Tail'         => 0,
-        'Time::TAI64'        => 0,
+        'File::Tail'         => 0,   # log/summarize, log/watch
+        'Time::TAI64'        => 0,   # log2sql
 #       'DBI'                => 0,   # auth_vpopmail_sql and
 #       'DBD::mysql'         => 0,   # log2sql
-#       'DBIx::Simple'       => 0,
+#       'DBIx::Simple'       => 0,   # log2sql
 # modules that cause Travis build tests to fail
 #       'Mail::SpamAssassin' => 0,
 #       'Geo::IP'            => 0,