Use \url{} to mark a URL.
diff --git a/Doc/libregex.tex b/Doc/libregex.tex
index 6843594..f3a3fa9 100644
--- a/Doc/libregex.tex
+++ b/Doc/libregex.tex
@@ -15,7 +15,7 @@
\code{reconvert}\refstmodindex{reconvert} helps in converting
\code{regex} style regular expressions to \code{re}\refstmodindex{re}
style regular expressions. (For more conversion help, see the URL
-\file{http://starship.skyport.net/crew/amk/regex/regex-to-re.html}.)
+\url{http://starship.skyport.net/crew/amk/regex/regex-to-re.html}.)
By default the patterns are Emacs-style regular expressions
(with one exception). There is