diff --git a/src/error.rs b/src/error.rs
index 597331b..63a657d 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -13,12 +13,10 @@ pub enum OreError {
     ResetTooEarly = 2,
     #[error("The provided hash was invalid")]
     HashInvalid = 3,
-    #[error("The provided hash does not satisfy the difficulty requirement")]
-    DifficultyNotSatisfied = 4,
     #[error("The bus does not have enough rewards to issue at this time")]
-    BusRewardsInsufficient = 5,
+    BusRewardsInsufficient = 4,
     #[error("The claim amount cannot be greater than the claimable rewards")]
-    ClaimTooLarge = 6,
+    ClaimTooLarge = 5,
 }
 
 impl From<OreError> for ProgramError {
diff --git a/src/instruction.rs b/src/instruction.rs
index fa60d43..3f049e8 100644
--- a/src/instruction.rs
+++ b/src/instruction.rs
@@ -197,6 +197,7 @@ pub fn register(signer: Pubkey) -> Instruction {
             AccountMeta::new(signer, true),
             AccountMeta::new(proof_pda.0, false),
             AccountMeta::new_readonly(solana_program::system_program::id(), false),
+            AccountMeta::new_readonly(sysvar::slot_hashes::id(), false),
         ],
         data: [
             OreInstruction::Register.to_vec(),
diff --git a/src/processor/mine.rs b/src/processor/mine.rs
index d7ee705..9241ad4 100644
--- a/src/processor/mine.rs
+++ b/src/processor/mine.rs
@@ -116,7 +116,7 @@ pub(crate) fn validate_hash(
         signer.as_ref(),
     ]);
     if hash.gt(&difficulty) {
-        return Err(OreError::DifficultyNotSatisfied.into());
+        return Err(OreError::HashInvalid.into());
     }
     Ok(hash)
 }
diff --git a/src/processor/register.rs b/src/processor/register.rs
index 94fc9fd..5451996 100644
--- a/src/processor/register.rs
+++ b/src/processor/register.rs
@@ -2,7 +2,7 @@ use std::mem::size_of;
 
 use solana_program::{
     account_info::AccountInfo, entrypoint::ProgramResult, keccak::hashv,
-    program_error::ProgramError, pubkey::Pubkey, system_program,
+    program_error::ProgramError, pubkey::Pubkey, slot_hashes::SlotHash, system_program, sysvar,
 };
 
 use crate::{
@@ -32,7 +32,7 @@ pub fn process_register<'a, 'info>(
     let args = RegisterArgs::try_from_bytes(data)?;
 
     // Load accounts
-    let [signer, proof_info, system_program] = accounts else {
+    let [signer, proof_info, system_program, slot_hashes_info] = accounts else {
         return Err(ProgramError::NotEnoughAccountKeys);
     };
     load_signer(signer)?;
@@ -43,6 +43,7 @@ pub fn process_register<'a, 'info>(
         &crate::id(),
     )?;
     load_program(system_program, system_program::id())?;
+    load_sysvar(slot_hashes_info, sysvar::slot_hashes::id())?;
 
     // Initialize proof
     create_pda(
@@ -58,7 +59,11 @@ pub fn process_register<'a, 'info>(
     let proof = Proof::try_from_bytes_mut(&mut proof_data)?;
     proof.authority = *signer.key;
     proof.claimable_rewards = 0;
-    proof.hash = hashv(&[signer.key.as_ref()]).into();
+    proof.hash = hashv(&[
+        signer.key.as_ref(),
+        &slot_hashes_info.data.borrow()[0..size_of::<SlotHash>()],
+    ])
+    .into();
     proof.total_hashes = 0;
     proof.total_rewards = 0;
 
diff --git a/tests/test_mine.rs b/tests/test_mine.rs
index 04faf3d..6494d5c 100644
--- a/tests/test_mine.rs
+++ b/tests/test_mine.rs
@@ -50,7 +50,6 @@ async fn test_mine() {
     let proof = Proof::try_from_bytes(&proof_account.data).unwrap();
     assert_eq!(proof.authority, payer.pubkey());
     assert_eq!(proof.claimable_rewards, 0);
-    assert_eq!(proof.hash, hashv(&[payer.pubkey().as_ref()]).into());
     assert_eq!(proof.total_hashes, 0);
     assert_eq!(proof.total_rewards, 0);
 
@@ -497,23 +496,6 @@ async fn test_mine_fail_bad_data() {
         assert!(res.is_err());
     }
 
-    // Fuzz test random hashes and nonces
-    for _ in 0..FUZZ {
-        let nonce: u64 = rng.gen();
-        assert_mine_tx_err(
-            &mut banks,
-            &payer,
-            blockhash,
-            payer.pubkey(),
-            BUS_ADDRESSES[0],
-            proof_address,
-            TREASURY_ADDRESS,
-            sysvar::slot_hashes::id(),
-            nonce,
-        )
-        .await;
-    }
-
     // Fuzz test random bus addresses
     for _ in 0..FUZZ {
         assert_mine_tx_err(
@@ -615,9 +597,9 @@ fn find_next_hash(hash: KeccakHash, difficulty: KeccakHash, signer: Pubkey) -> (
     let mut nonce = 0u64;
     loop {
         next_hash = hashv(&[
+            nonce.to_le_bytes().as_slice(),
             hash.to_bytes().as_slice(),
             signer.to_bytes().as_slice(),
-            nonce.to_le_bytes().as_slice(),
         ]);
         if next_hash.le(&difficulty) {
             break;