diff --git a/sys/Makefile b/sys/Makefile
index 3b24ed95ca54..969994f80ae9 100644
--- a/sys/Makefile
+++ b/sys/Makefile
@@ -12,7 +12,7 @@ CSCOPEDIRS=	boot bsm cam cddl compat conf contrib crypto ddb dev fs gdb \
 		geom gnu isa kern libkern modules net net80211 netatalk \
 		netgraph netinet netinet6 netipsec netipx netnatm netncp \
 		netsmb nfs nfsclient nfsserver nlm opencrypto \
-		pci rpc security sys ufs vm xdr ${CSCOPE_ARCHDIR}
+		pci rpc security sys ufs vm xdr xen ${CSCOPE_ARCHDIR}
 .if defined(ALL_ARCH)
 CSCOPE_ARCHDIR ?= amd64 arm i386 ia64 mips pc98 powerpc sparc64 x86
 .else