--- a/s3270/Makefile.obj.in
+++ b/s3270/Makefile.obj.in
@@ -69,7 +69,7 @@
 	./mkfb -c -o $@ $(filter-out mkfb,$^)
 
 mkfb: mkfb.c
-	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(filter %.c,$^)
+	$(CC_FOR_BUILD) $(XCPPFLAGS) -o $@ $(filter %.c,$^)
 
 s3270: $(OBJS1) $(DEP3270) $(DEP32XX) $(DEP3270STUBS)
 	$(CC) -o $@ $(OBJS1) $(LDFLAGS) $(LD3270) $(LD32XX) $(LD3270STUBS) $(LIBS)
