--- hol88-2.02.19940316.orig/Manual/Makefile
+++ hol88-2.02.19940316/Manual/Makefile
@@ -41,3 +41,5 @@
 	make tutorial;make description; make reference;make libraries;make covers
 	@echo "=======> MANUAL made"
 
+clean:
+	for i in Tutorial Description Reference Libraries Covers ; do $(MAKE) -C $$i clean ; done