diff --git a/nemu/tools/spike-diff/Makefile b/nemu/tools/spike-diff/Makefile
index 760d427..b97e4ca 100644
--- a/nemu/tools/spike-diff/Makefile
+++ b/nemu/tools/spike-diff/Makefile
@@ -15,7 +15,7 @@
 
 REPO_PATH = repo
 ifeq ($(wildcard repo/spike_main),)
-  $(shell git clone --depth=1 https://github.com/NJU-ProjectN/riscv-isa-sim $(REPO_PATH))
+  $(shell git clone --depth=1 https://www.github.com/NJU-ProjectN/riscv-isa-sim $(REPO_PATH))
 endif
 
 REPO_BUILD_PATH = $(REPO_PATH)/build