diff --git a/doc/src/sgml/Makefile b/doc/src/sgml/Makefile
index fe7ca65..897c9c9 100644
--- a/doc/src/sgml/Makefile
+++ b/doc/src/sgml/Makefile
@@ -410,6 +410,6 @@ distclean: clean
 
 maintainer-clean: distclean
 # HTML
-	rm -fr html/ html-stamp
+	rm -fr html/ html-stamp oldhtml-stamp
 # man
 	rm -rf man1/ man3/ man7/ man-stamp