diff --git a/nemu/tests/expr_test.c b/nemu/tests/expr_test.c
index ee8611e..449411a 100644
--- a/nemu/tests/expr_test.c
+++ b/nemu/tests/expr_test.c
@@ -174,6 +174,7 @@ START_TEST(test_expr_plain_register) {
   for (i = 1; i < 32; i++) {
     ck_assert(strcpy(buf + 1, regs[i]));
     gpr(i) = i;
+    printf("%d: %s\n", i, buf);
     yy_scan_string(buf);
     uint32_t value;
     ck_assert(!yyparse(&value));