diff --git a/Doc/perl/python.perl b/Doc/perl/python.perl
index a0cb70c..48e3115 100644
--- a/Doc/perl/python.perl
+++ b/Doc/perl/python.perl
@@ -158,6 +158,9 @@
 
 sub codetext($){
     my $text = "$_[0]";
+    # Make sure that "---" is not converted to "--" later when
+    # LaTeX2HTML tries converting em-dashes based on the conventional
+    # TeX font ligatures:
     $text =~ s/--/-\&#45;/go;
     return $text;
 }