diff --git a/qemu/target/riscv/vector_helper.c b/qemu/target/riscv/vector_helper.c
index b29f70fa..ece7cad9 100644
--- a/qemu/target/riscv/vector_helper.c
+++ b/qemu/target/riscv/vector_helper.c
@@ -152,8 +152,8 @@ static void vext_clear(void *tail, uint32_t cnt, uint32_t tot)
     if (cnt % 8) {
         part1 = 8 - (cnt % 8);
         part2 = tot - cnt - part1;
-        memset((void *)((uintptr_t)tail & ~(7ULL)), 0, part1);
-        memset((void *)(((uintptr_t)tail + 8) & ~(7ULL)), 0, part2);
+        memset(QEMU_ALIGN_PTR_DOWN(tail, 8), 0, part1);
+        memset(QEMU_ALIGN_PTR_UP(tail, 8), 0, part2);
     } else {
         memset(tail, 0, part2);
     }