diff --git a/nemu/tests/expr_test.c b/nemu/tests/expr_test.c
index 60d680c..ee8611e 100644
--- a/nemu/tests/expr_test.c
+++ b/nemu/tests/expr_test.c
@@ -171,7 +171,7 @@ START_TEST(test_expr_plain_register) {
   char buf[5] = {};
   // NOTE: need to fix this if want to support more arch
   buf[0] = '$';
-  for (i = 0; i < 32; i++) {
+  for (i = 1; i < 32; i++) {
     ck_assert(strcpy(buf + 1, regs[i]));
     gpr(i) = i;
     yy_scan_string(buf);