diff --git a/sys/modules/efirt/Makefile b/sys/modules/efirt/Makefile
index 9ea861836c22..58f4f9673c2e 100644
--- a/sys/modules/efirt/Makefile
+++ b/sys/modules/efirt/Makefile
@@ -11,6 +11,7 @@ SRCS+=  device_if.h bus_if.h clock_if.h
 .if ${MACHINE_CPUARCH} == "amd64"
 SRCS+=	opt_hwpmc_hooks.h opt_kstack_pages.h
 SRCS+=	efirt_support.S
+DPSRCS+= assym.inc
 efirt_support.o:	efirt_support.S assym.inc
 	${CC} -c -x assembler-with-cpp -DLOCORE ${CFLAGS} \
 	    ${.IMPSRC} -o ${.TARGET}