-AC_CHECK_PROG(DEBIANDOC_HTML,debiandoc2html,"yes","")
-AC_CHECK_PROG(DEBIANDOC_TEXT,debiandoc2text,"yes","")
+AC_PATH_PROG(DEBIANDOC_HTML,debiandoc2html)
+AC_PATH_PROG(DEBIANDOC_TEXT,debiandoc2text)
+
+dnl Check for doxygen
+AC_PATH_PROG(DOXYGEN, doxygen)
+
+dnl Check for the SGML tools needed to build man pages
+AC_PATH_PROG(DOCBOOK2MAN,docbook2man)
+
+dnl Check for the XML tools needed to build man pages
+AC_PATH_PROG(XMLTO,xmlto)
+
+dnl Check for graphviz
+AC_CHECK_PROG([HAVE_DOT], [dot], [YES], [NO])
+AC_PATH_PROG([DOT], [dot], [])
+DOTDIR=$(dirname $DOT)
+AC_SUBST(DOTDIR)