diff --git a/rbutil/mkamsboot/Makefile b/rbutil/mkamsboot/Makefile
index d1bed217ba..8ee44cd389 100644
--- a/rbutil/mkamsboot/Makefile
+++ b/rbutil/mkamsboot/Makefile
@@ -47,6 +47,10 @@ OBJS := $(patsubst %.c,%.o,$(addprefix $(OBJDIR),$(SOURCES)))
 LIBOBJS := $(patsubst %.c,%.o,$(addprefix $(OBJDIR),$(LIBSOURCES)))
 EXTRADEPS := $(LIBUCL)
 
+# explicit dependencies on dualboot.{c,h}
+$(OBJDIR)mkamsboot.o: dualboot.h dualboot.c mkamsboot.c
+$(OBJDIR)main.o: dualboot.h dualboot.c main.c
+
 $(OBJDIR)%.o: %.c
 	@echo CC $< $
 	$(SILENT)mkdir -p $(dir $@)