diff --git a/Makefile b/Makefile
index 2c7c33855..66c8b4b12 100644
--- a/Makefile
+++ b/Makefile
@@ -760,6 +760,8 @@ $(LIB_FILE): $(LIB_OBJS)
 	rm -f $@ && $(AR) rcs $@ $(LIB_OBJS)
 
 XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o
+$(XDIFF_OBJS): xdiff/xinclude.h xdiff/xmacros.h xdiff/xdiff.h xdiff/xtypes.h \
+	xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h
 
 $(XDIFF_LIB): $(XDIFF_OBJS)
 	rm -f $@ && $(AR) rcs $@ $(XDIFF_OBJS)