Index: sys/conf/files.amd64
===================================================================
--- sys/conf/files.amd64
+++ sys/conf/files.amd64
@@ -105,7 +105,7 @@
 #
 amd64/acpica/acpi_machdep.c	optional	acpi
 acpi_wakecode.o			optional	acpi			\
-	dependency	"$S/amd64/acpica/acpi_wakecode.S assym.s"	\
+	dependency	"$S/amd64/acpica/acpi_wakecode.S assym.S"	\
 	compile-with	"${NORMAL_S}"					\
 	no-obj no-implicit-rule before-depend				\
 	clean		"acpi_wakecode.o"
Index: sys/conf/files.i386
===================================================================
--- sys/conf/files.i386
+++ sys/conf/files.i386
@@ -439,7 +439,7 @@
 dev/isci/scil/scif_sas_timer.c					optional isci
 i386/acpica/acpi_machdep.c	optional acpi
 acpi_wakecode.o			optional acpi				\
-	dependency	"$S/i386/acpica/acpi_wakecode.S assym.s"	\
+	dependency	"$S/i386/acpica/acpi_wakecode.S assym.S"	\
 	compile-with	"${NORMAL_S}"					\
 	no-obj no-implicit-rule before-depend				\
 	clean		"acpi_wakecode.o"
Index: sys/conf/kern.post.mk
===================================================================
--- sys/conf/kern.post.mk
+++ sys/conf/kern.post.mk
@@ -154,7 +154,7 @@
 .endif
 	${SYSTEM_LD_TAIL}
 
-OBJS_DEPEND_GUESS+=	assym.s vnode_if.h ${BEFORE_DEPEND:M*.h} \
+OBJS_DEPEND_GUESS+=	assym.S vnode_if.h ${BEFORE_DEPEND:M*.h} \
 			${MFILES:T:S/.m$/.h/}
 
 .for mfile in ${MFILES}
@@ -183,7 +183,7 @@
 	${CC} ${HACK_EXTRA_FLAGS} -nostdlib hack.c -o hack.pico
 	rm -f hack.c
 
-assym.s: $S/kern/genassym.sh genassym.o
+assym.S: $S/kern/genassym.sh genassym.o
 	NM='${NM}' NMFLAGS='${NMFLAGS}' sh $S/kern/genassym.sh genassym.o > ${.TARGET}
 
 genassym.o: $S/$M/$M/genassym.c
@@ -209,7 +209,7 @@
 .endif
 
 kernel-depend: .depend
-SRCS=	assym.s vnode_if.h ${BEFORE_DEPEND} ${CFILES} \
+SRCS=	assym.S vnode_if.h ${BEFORE_DEPEND} ${CFILES} \
 	${SYSTEM_CFILES} ${GEN_CFILES} ${SFILES} \
 	${MFILES:T:S/.m$/.h/}
 DEPENDOBJS+=	${SYSTEM_OBJS} genassym.o
Index: sys/conf/kmod.mk
===================================================================
--- sys/conf/kmod.mk
+++ sys/conf/kmod.mk
@@ -454,14 +454,14 @@
 	${AWK} -f ${SYSDIR}/tools/acpi_quirks2h.awk ${SYSDIR}/dev/acpica/acpi_quirks
 .endif
 
-.if !empty(SRCS:Massym.s) || !empty(DPSRCS:Massym.s)
-CLEANFILES+=	assym.s genassym.o
+.if !empty(SRCS:Massym.S) || !empty(DPSRCS:Massym.S)
+CLEANFILES+=	assym.S genassym.o
 DEPENDOBJS+=	genassym.o
-assym.s: genassym.o
+assym.S: genassym.o
 .if defined(KERNBUILDDIR)
 genassym.o: opt_global.h
 .endif
-assym.s: ${SYSDIR}/kern/genassym.sh
+assym.S: ${SYSDIR}/kern/genassym.sh
 	sh ${SYSDIR}/kern/genassym.sh genassym.o > ${.TARGET}
 genassym.o: ${SYSDIR}/${MACHINE}/${MACHINE}/genassym.c
 genassym.o: ${SRCS:Mopt_*.h}