diff --git a/doc/Makefile b/doc/Makefile
index af6c27d..9896981 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -7,6 +7,8 @@ all : doc
 
 doc : index.html
 
+index.html : *.asciidoc
+
 clean :
 	rm -f index.html