diff --git a/src/rpc.rs b/src/rpc.rs
index ec1dd5f..837b848 100644
--- a/src/rpc.rs
+++ b/src/rpc.rs
@@ -17,6 +17,7 @@ use serde::Serialize;
 #[derive(Clone)]
 pub(crate) struct MiningParams {
     pub(crate) pre_hash: H256,
+    pub(crate) rot: [u8; 4],
     pub(crate) parent_hash: H256,
     pub(crate) win_difficulty: U256,
     pub(crate) pow_difficulty: U256,
@@ -183,9 +184,27 @@ impl MiningContext {
                 pub_key.reverse();
                 let pub_key = ecies_ed25519::PublicKey::from_bytes(&pub_key).unwrap();
 
+                let rot_hash = match self.p3d_params.algo {
+                    AlgoType::Grid2dV3_1 | AlgoType::Grid2dV3a => pre_hash,
+                    _ => parent_hash,
+                };
+
+                let mut r: [u8;32] = rot_hash.encode()[0..32].try_into().unwrap();
+                if matches!(self.p3d_params.algo, AlgoType::Grid2dV3a) {
+                    for a in r[3..].iter() {
+                        // exclude rotation less than 20
+                        if *a > 20 {
+                            r[3] = a.clone();
+                            break;
+                        }
+                    }
+                }
+                let rot: [u8; 4] = r[0..4].try_into().unwrap();
+
                 let mut lock = self.cur_state.lock().unwrap();
                 (*lock) = Some(MiningParams {
                     pre_hash,
+                    rot,
                     parent_hash,
                     win_difficulty,
                     pow_difficulty,
diff --git a/src/worker.rs b/src/worker.rs
index 7fd3026..5eb3097 100644
--- a/src/worker.rs
+++ b/src/worker.rs
@@ -1,5 +1,4 @@
 use std::collections::HashSet;
-use std::convert::TryInto;
 use std::f32::consts::PI;
 use std::fmt::Write;
 use std::str::FromStr;
@@ -20,7 +19,7 @@ use rayon::prelude::*;
 use sha3::{Digest, Sha3_256};
 use tokio::time;
 
-use crate::rpc::{AlgoType, MiningObj, MiningProposal};
+use crate::rpc::{MiningObj, MiningProposal};
 
 use super::MiningContext;
 use super::P3dParams;
@@ -79,16 +78,11 @@ pub(crate) fn worker(ctx: &MiningContext) {
 
         let MiningParams {
             pre_hash,
-            parent_hash,
+            rot,
             win_difficulty,
             pow_difficulty,
             ..
         } = mining_params;
-        let rot_hash = match &algo {
-            AlgoType::Grid2dV3_1 | AlgoType::Grid2dV3a => pre_hash,
-            _ => parent_hash,
-        };
-        let rot = rot_hash.encode()[0..4].try_into().ok();
 
         let mining_obj: MiningObj = MiningObj {
             obj_id: 1,
@@ -100,7 +94,7 @@ pub(crate) fn worker(ctx: &MiningContext) {
             algo.as_p3d_algo(),
             grid as i16,
             sect as i16,
-            rot,
+            Some(rot),
         );
 
         let (first_hash, obj_hash, poscan_hash) = match res_hashes {