diff --git a/target/riscv/vector_internals.c b/target/riscv/vector_internals.c
index 9cf5c17cdeacad77952935a99d9e2021f813047e..be6eb040d223bc01372f31e55584a85698b170a9 100644
--- a/target/riscv/vector_internals.c
+++ b/target/riscv/vector_internals.c
@@ -29,6 +29,28 @@ void vext_set_elems_1s(void *base, uint32_t is_agnostic, uint32_t cnt,
     if (tot - cnt == 0) {
         return ;
     }
+
+    if (HOST_BIG_ENDIAN) {
+        /*
+         * Deal the situation when the elements are insdie
+         * only one uint64 block including setting the
+         * masked-off element.
+         */
+        if (((tot - 1) ^ cnt) < 8) {
+            memset(base + H1(tot - 1), -1, tot - cnt);
+            return;
+        }
+        /*
+         * Otherwise, at least cross two uint64_t blocks.
+         * Set first unaligned block.
+         */
+        if (cnt % 8 != 0) {
+            uint32_t j = ROUND_UP(cnt, 8);
+            memset(base + H1(j - 1), -1, j - cnt);
+            cnt = j;
+        }
+        /* Set other 64bit aligend blocks */
+    }
     memset(base + cnt, -1, tot - cnt);
 }