diff --git a/nemu/scripts/build.mk b/nemu/scripts/build.mk
index 07c3c79..e6c11bb 100644
--- a/nemu/scripts/build.mk
+++ b/nemu/scripts/build.mk
@@ -45,11 +45,23 @@ $(OBJ_DIR)/%.tag.c: %.y
 	@mkdir -p $(dir $@)
 	@$(YACC) $(YFLAGS) --header=$(<:.y=.h) -o $@ $<
 
+$(OBJ_DIR)/%.tag.o: $(OBJ_DIR)/%.tag.c
+	@echo + CC $<
+	@mkdir -p $(dir $@)
+	@$(CC) $(CFLAGS) -c -o $@ $<
+	$(call call_fixdep, $(@:.o=.d), $@)
+
 $(OBJ_DIR)/%.yy.c: %.l $(OBJ_DIR)/%.tag.c
 	@echo + LEX $<
 	@mkdir -p $(dir $@)
 	@$(LEX) $(LFLAGS) -o $@ $<
 
+$(OBJ_DIR)/%.yy.o: %(OBJ_DIR)/%.yy.c
+	@echo + CC $<
+	@mkdir -p $(dir $@)
+	@$(CC) $(CFLAGS) -c -o $@ $<
+	$(call call_fixdep, $(@:.o=.d), $@)
+
 # Depencies
 -include $(OBJS:.o=.d)