diff --git a/nemu/tests/expr_test.c b/nemu/tests/expr_test.c
index c5f874b..a3f28d5 100644
--- a/nemu/tests/expr_test.c
+++ b/nemu/tests/expr_test.c
@@ -152,7 +152,7 @@ struct {
     {"0--0x1", 0x1},
 }, reg_exprs[] = {
     {"$ra", 0x1},
-    {"4*$ra", 0x4},
+    {"0x2 + 4*-$a7", 0xFFFFFFBEU},
 };
 START_TEST(test_expr_negative_operand) {
   yy_scan_string(exprs[_i].expr);