diff --git a/Makefile.in b/Makefile.in
index 7b8cce0d080d4b4693b6a82bb262b8d55a675624..d57a5c63faafdd02745b1df10f85cbf77a813f4a 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -147,7 +147,7 @@ $(des_headers): desdata.c
 	./desdata$(EXEEXT) $(@F) > $@T
 	test -s $@T && mv -f $@T $@
 
-des.o: des.c des.h $(des_headers)
+des.$(OBJEXT): des.c des.h $(des_headers)
 
 .asm.$(OBJEXT):
 	$(M4) $(srcdir)/asm.m4 machine.m4 config.m4 \