diff --git a/nemu/tests/expr_test.c b/nemu/tests/expr_test.c
index 0870fdb..0c5b33b 100644
--- a/nemu/tests/expr_test.c
+++ b/nemu/tests/expr_test.c
@@ -10,6 +10,7 @@
 #include <time.h>
 #include <addrexp.h>
 #include <addrexp_lex.h>
+#include <common.h>
 #include <reg.h>
 
 char buf[65536] = {}, ref_buf[65536] = {};