diff --git a/nemu/tests/expr_test.c b/nemu/tests/expr_test.c
index 8ffbc6a..df65db0 100644
--- a/nemu/tests/expr_test.c
+++ b/nemu/tests/expr_test.c
@@ -173,6 +173,7 @@ START_TEST(test_expr_plain_register) {
   buf[0] = '$';
   for (i = 0; i < 32; i++) {
     ck_assert(strcpy(buf + 1, regs[i]));
+    puts(buf);
     gpr(i) = i;
   }
   yy_scan_string(buf);