diff --git a/src/libcharon/Makefile.am b/src/libcharon/Makefile.am
index 7192e3db7..4d3cc39c7 100644
--- a/src/libcharon/Makefile.am
+++ b/src/libcharon/Makefile.am
@@ -500,3 +500,9 @@ if MONOLITHIC
 endif
 endif
 
+if USE_XAUTH_NULL
+  SUBDIRS += plugins/xauth_null
+if MONOLITHIC
+  libcharon_la_LIBADD += plugins/xauth_null/libstrongswan-xauth-null.la
+endif
+endif