--- ./tools/qemu-xen-traditional/Makefile.target.orig
+++ ./tools/qemu-xen-traditional/Makefile.target
@@ -520,7 +520,7 @@
 OBJS+=block-raw-posix.o
 endif
 
-LIBS+=-lz
+LIBS+=-lz -lrt
 ifdef CONFIG_ALSA
 LIBS += -lasound
 endif