diff --git a/virtio-devices/src/vsock/packet.rs b/virtio-devices/src/vsock/packet.rs
index 3afd40550..dcec00183 100644
--- a/virtio-devices/src/vsock/packet.rs
+++ b/virtio-devices/src/vsock/packet.rs
@@ -555,12 +555,11 @@ mod unit_tests {
 
     fn set_pkt_len(len: u32, guest_desc: &GuestQDesc, mem: &GuestMemoryMmap) {
         let hdr_gpa = guest_desc.addr.get();
-        let hdr_ptr =
-            get_host_address_range(mem, GuestAddress(hdr_gpa), VSOCK_PKT_HDR_SIZE).unwrap();
-        // SAFETY: The length is valid.
-        let len_ptr = unsafe { hdr_ptr.add(HDROFF_LEN) };
-        // SAFETY: The length is valid.
-        LittleEndian::write_u32(unsafe { std::slice::from_raw_parts_mut(len_ptr, 4) }, len);
+        mem.write_slice(
+            &len.to_le_bytes(),
+            GuestAddress(hdr_gpa + HDROFF_LEN as u64),
+        )
+        .expect("test packet header len field should be in guest memory");
     }
 
     #[test]