diff --git a/Makefile.am b/Makefile.am
index d6d78b90..f89c0bc0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -55,7 +55,8 @@ man_MANS = event.3 evdns.3
 verify: libevent.la
 	cd test && make verify
 
-doxygen:
+doxygen: FORCE
 	doxygen $(srcdir)/Doxyfile
+FORCE:
 
 DISTCLEANFILES = *~