diff --git a/Makefile.doc b/Makefile.doc
index 160dad0..d127e78 100644
--- a/Makefile.doc
+++ b/Makefile.doc
@@ -1,2 +1,7 @@
+all: puzzles.hlp puzzles.txt HACKING
+
 puzzles.hlp puzzles.txt: puzzles.but
 	halibut --winhelp=puzzles.hlp --text=puzzles.txt puzzles.but
+
+HACKING: HACKING.but
+	halibut --text=HACKING HACKING.but