diff --git a/board/r7780mp/Makefile b/board/r7780mp/Makefile
index f0f1c97..34ce9a8 100644
--- a/board/r7780mp/Makefile
+++ b/board/r7780mp/Makefile
@@ -20,11 +20,15 @@
 
 include $(TOPDIR)/config.mk
 
-LIB	= lib$(BOARD).a
+LIB	= $(obj)lib$(BOARD).a
 
 OBJS	:= r7780mp.o
 SOBJS	:= lowlevel_init.o
 
+SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(COBJS))
+SOBJS	:= $(addprefix $(obj),$(SOBJS))
+
 $(LIB):	$(OBJS) $(SOBJS)
 	$(AR) $(ARFLAGS) $@ $(OBJS) $(SOBJS)
 
@@ -36,9 +40,9 @@
 
 #########################################################################
 
-.depend:	Makefile $(SOBJS:.o=.S) $(OBJS:.o=.c)
-		$(CC) -M $(CPPFLAGS) $(SOBJS:.o=.S) $(OBJS:.o=.c) > $@
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
 
--include .depend
+sinclude $(obj).depend
 
 #########################################################################