diff --git a/nemu/Makefile b/nemu/Makefile
index 4c7ed77..0f360fe 100644
--- a/nemu/Makefile
+++ b/nemu/Makefile
@@ -40,7 +40,9 @@ SRCS-y += $(shell find -L $(DIRS-y) -name "*.c")
 SRCS = $(filter-out $(SRCS-BLACKLIST-y),$(SRCS-y))
 
 # Extract compiler and options from menuconfig
+ifneq ($(CONFIG_CC),)
 CC = $(call remove_quote,$(CONFIG_CC))
+endif
 CFLAGS_BUILD += $(call remove_quote,$(CONFIG_CC_OPT))
 CFLAGS_BUILD += $(if $(CONFIG_CC_LTO),-flto,)
 CFLAGS_BUILD += $(if $(CONFIG_CC_DEBUG),-Og -ggdb3,)