diff --git a/api/src/instruction.rs b/api/src/instruction.rs
index db53ab9..e5025fd 100644
--- a/api/src/instruction.rs
+++ b/api/src/instruction.rs
@@ -8,16 +8,17 @@ pub enum OreInstruction {
     Close = 1,
     Commit = 2,
     Deposit = 3,
-    Mine = 4,
-    Swap = 5,
-    Uncommit = 6,
-    Withdraw = 7,
+    Log = 4,
+    Mine = 5,
+    Swap = 6,
+    Uncommit = 7,
+    Withdraw = 8,
 
     // Admin
-    SetAdmin = 8,
-    SetBlockLimit = 9,
-    SetFeeCollector = 10,
-    SetFeeRate = 11,
+    SetAdmin = 9,
+    SetBlockLimit = 10,
+    SetFeeCollector = 11,
+    SetFeeRate = 12,
 }
 
 #[repr(C)]
@@ -45,6 +46,10 @@ pub struct Deposit {
     pub amount: [u8; 8],
 }
 
+#[repr(C)]
+#[derive(Clone, Copy, Debug, Pod, Zeroable)]
+pub struct Log {}
+
 #[repr(C)]
 #[derive(Clone, Copy, Debug, Pod, Zeroable)]
 pub struct Mine {
@@ -99,6 +104,7 @@ instruction!(OreInstruction, Open);
 instruction!(OreInstruction, Close);
 instruction!(OreInstruction, Commit);
 instruction!(OreInstruction, Deposit);
+instruction!(OreInstruction, Log);
 instruction!(OreInstruction, Mine);
 instruction!(OreInstruction, Swap);
 instruction!(OreInstruction, Uncommit);
diff --git a/api/src/sdk.rs b/api/src/sdk.rs
index b10ffb2..7e7729f 100644
--- a/api/src/sdk.rs
+++ b/api/src/sdk.rs
@@ -2,7 +2,7 @@ use spl_associated_token_account::get_associated_token_address;
 use steel::*;
 
 use crate::{
-    consts::{MINT_ADDRESS, TREASURY_ADDRESS},
+    consts::{BLOCK, MINT_ADDRESS, TREASURY_ADDRESS},
     instruction::*,
     state::*,
 };
@@ -87,6 +87,25 @@ pub fn close(
     }
 }
 
+pub fn log(signer: Pubkey, msg: &[u8]) -> Instruction {
+    let mut data = Log {}.to_bytes();
+    data.extend_from_slice(msg);
+    Instruction {
+        program_id: crate::ID,
+        accounts: vec![AccountMeta::new(signer, true)],
+        data: data,
+    }
+}
+
+pub fn program_log(block_id: u64, block_info: AccountInfo, msg: &[u8]) -> Result<(), ProgramError> {
+    invoke_signed(
+        &log(*block_info.key, msg),
+        &[block_info.clone()],
+        &crate::ID,
+        &[BLOCK, &block_id.to_le_bytes()],
+    )
+}
+
 pub fn mine(signer: Pubkey, id: u64, amount: u64) -> Instruction {
     let block_adddress = block_pda(id).0;
     let market_address = market_pda(id).0;
diff --git a/program/src/close.rs b/program/src/close.rs
index f4b4da0..c633e38 100644
--- a/program/src/close.rs
+++ b/program/src/close.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Closes a block.
@@ -58,7 +58,6 @@ pub fn process_close(accounts: &[AccountInfo<'_>], _data: &[u8]) -> ProgramResul
     if block.reward.lode_reward > 0 && block.reward.lode_authority != Pubkey::default() {
         // Load recipient.
         recipient_info.as_associated_token_account(&block.reward.lode_authority, &MINT_ADDRESS)?;
-
         let miner = miner_info
             .as_account_mut::<Miner>(&ore_api::ID)?
             .assert_mut(|m| m.authority == block.reward.lode_authority)?;
@@ -173,14 +172,18 @@ pub fn process_close(accounts: &[AccountInfo<'_>], _data: &[u8]) -> ProgramResul
     market_info.close(opener_info)?;
 
     // Emit event.
-    CloseEvent {
-        authority: *signer_info.key,
-        id: block.id,
-        burned_base: base_burned,
-        burned_quote: quote_burned,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &CloseEvent {
+            authority: *signer_info.key,
+            id: block.id,
+            burned_base: base_burned,
+            burned_quote: quote_burned,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/commit.rs b/program/src/commit.rs
index cc7c68e..2fb3dcc 100644
--- a/program/src/commit.rs
+++ b/program/src/commit.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Commit to a block.
@@ -25,7 +25,6 @@ pub fn process_commit(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResul
         .as_token_account()?
         .assert(|t| t.mint() == *mint_info.key)?
         .assert(|t| t.owner() == *block_info.key)?;
-    // commitment_info.as_associated_token_account(block_info.key, mint_info.key)?;
     let market = market_info
         .as_account::<Market>(&ore_api::ID)?
         .assert(|m| m.id == block.id)?;
@@ -106,16 +105,20 @@ pub fn process_commit(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResul
     block.total_committed += amount;
 
     // Emit event.
-    CommitEvent {
-        disc: OreEvent::Commit as u64,
-        authority: *signer_info.key,
-        block_id: block.id,
-        amount,
-        block_commitment: block.total_committed,
-        permit_commitment: permit.commitment,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &CommitEvent {
+            disc: OreEvent::Commit as u64,
+            authority: *signer_info.key,
+            block_id: block.id,
+            amount,
+            block_commitment: block.total_committed,
+            permit_commitment: permit.commitment,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/deposit.rs b/program/src/deposit.rs
index 537f955..8c65fea 100644
--- a/program/src/deposit.rs
+++ b/program/src/deposit.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Deposits collateral.
@@ -67,15 +67,19 @@ pub fn process_deposit(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResu
     )?;
 
     // Emit event.
-    DepositEvent {
-        disc: OreEvent::Deposit as u64,
-        authority: *signer_info.key,
-        block_id: block.id,
-        amount,
-        collateral: stake.collateral,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &DepositEvent {
+            disc: OreEvent::Deposit as u64,
+            authority: *signer_info.key,
+            block_id: block.id,
+            amount,
+            collateral: stake.collateral,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/lib.rs b/program/src/lib.rs
index d696404..d63b7d5 100644
--- a/program/src/lib.rs
+++ b/program/src/lib.rs
@@ -1,6 +1,7 @@
 mod close;
 mod commit;
 mod deposit;
+mod log;
 mod mine;
 mod open;
 mod set_admin;
@@ -14,6 +15,7 @@ mod withdraw;
 use close::*;
 use commit::*;
 use deposit::*;
+use log::*;
 use mine::*;
 use open::*;
 use set_admin::*;
@@ -39,6 +41,7 @@ pub fn process_instruction(
         OreInstruction::Close => process_close(accounts, data)?,
         OreInstruction::Commit => process_commit(accounts, data)?,
         OreInstruction::Deposit => process_deposit(accounts, data)?,
+        OreInstruction::Log => process_log(accounts, data)?,
         OreInstruction::Mine => process_mine(accounts, data)?,
         OreInstruction::Swap => process_swap(accounts, data)?,
         OreInstruction::Uncommit => process_uncommit(accounts, data)?,
diff --git a/program/src/log.rs b/program/src/log.rs
new file mode 100644
index 0000000..53f8e39
--- /dev/null
+++ b/program/src/log.rs
@@ -0,0 +1,15 @@
+use ore_api::prelude::*;
+use steel::*;
+
+/// No-op, use instruction data for logging w/o truncation.
+pub fn process_log(accounts: &[AccountInfo<'_>], _data: &[u8]) -> ProgramResult {
+    // Load accounts.
+    let [signer_info] = accounts else {
+        return Err(ProgramError::NotEnoughAccountKeys);
+    };
+    signer_info.as_account::<Block>(&ore_api::ID)?;
+
+    // For data integrity, only a block can log messages.
+
+    Ok(())
+}
diff --git a/program/src/mine.rs b/program/src/mine.rs
index b5ccd9a..4bf2be3 100644
--- a/program/src/mine.rs
+++ b/program/src/mine.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use solana_nostd_keccak::hash;
 use solana_program::slot_hashes::SlotHashes;
 use steel::*;
@@ -139,27 +139,35 @@ pub fn process_mine(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResult
         )?;
 
         // Emit event.
-        RewardEvent {
-            disc: OreEvent::Reward as u64,
-            amount: reward_amount,
-            authority: miner.authority,
-            block_id: block.id,
-            rewards_type: RewardsType::Nugget as u64,
-            ts: clock.unix_timestamp,
-        }
-        .log();
+        program_log(
+            block.id,
+            block_info.clone(),
+            &RewardEvent {
+                disc: OreEvent::Reward as u64,
+                amount: reward_amount,
+                authority: miner.authority,
+                block_id: block.id,
+                rewards_type: RewardsType::Nugget as u64,
+                ts: clock.unix_timestamp,
+            }
+            .to_bytes(),
+        )?;
     }
 
     // Emit event.
-    MineEvent {
-        disc: OreEvent::Mine as u64,
-        authority: miner.authority,
-        block_id: block.id,
-        deployed: amount,
-        total_deployed: block.total_deployed,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &MineEvent {
+            disc: OreEvent::Mine as u64,
+            authority: miner.authority,
+            block_id: block.id,
+            deployed: amount,
+            total_deployed: block.total_deployed,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/open.rs b/program/src/open.rs
index f90b6d9..2c562cf 100644
--- a/program/src/open.rs
+++ b/program/src/open.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use solana_nostd_keccak::hash;
 use solana_program::program_pack::Pack;
 use spl_token_2022::instruction::AuthorityType;
@@ -313,17 +313,21 @@ pub fn process_open(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResult
     )?;
 
     // Emit event.
-    OpenEvent {
-        disc: OreEvent::Open as u64,
-        id,
-        start_slot,
-        signer: *signer_info.key,
-        reward_config: block.reward,
-        liquidity_base: market.base.liquidity() as u64,
-        liquidity_quote: market.quote.liquidity() as u64,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &OpenEvent {
+            disc: OreEvent::Open as u64,
+            id,
+            start_slot,
+            signer: *signer_info.key,
+            reward_config: block.reward,
+            liquidity_base: market.base.liquidity() as u64,
+            liquidity_quote: market.quote.liquidity() as u64,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/swap.rs b/program/src/swap.rs
index 4e52412..3190b48 100644
--- a/program/src/swap.rs
+++ b/program/src/swap.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Swap in a hashpower market.
@@ -137,7 +137,7 @@ pub fn process_swap(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResult
     market.check_vaults(&vault_base, &vault_quote)?;
 
     // Emit event.
-    swap_event.log_return();
+    program_log(block.id, block_info.clone(), &swap_event.to_bytes())?;
 
     Ok(())
 }
diff --git a/program/src/uncommit.rs b/program/src/uncommit.rs
index 3a22dda..bbbd153 100644
--- a/program/src/uncommit.rs
+++ b/program/src/uncommit.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Uncommit from a block.
@@ -65,16 +65,20 @@ pub fn process_uncommit(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramRes
     }
 
     // Emit event.
-    UncommitEvent {
-        disc: OreEvent::Uncommit as u64,
-        authority: *signer_info.key,
-        block_id: block.id,
-        block_commitment: block.total_committed,
-        permit_commitment: permit.commitment,
-        amount,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        block.id,
+        block_info.clone(),
+        &UncommitEvent {
+            disc: OreEvent::Uncommit as u64,
+            authority: *signer_info.key,
+            block_id: block.id,
+            block_commitment: block.total_committed,
+            permit_commitment: permit.commitment,
+            amount,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }
diff --git a/program/src/withdraw.rs b/program/src/withdraw.rs
index 9dfe86e..6670d00 100644
--- a/program/src/withdraw.rs
+++ b/program/src/withdraw.rs
@@ -1,4 +1,4 @@
-use ore_api::prelude::*;
+use ore_api::{prelude::*, sdk::program_log};
 use steel::*;
 
 /// Withdraws collateral.
@@ -57,15 +57,19 @@ pub fn process_withdraw(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramRes
     }
 
     // Emit event.
-    WithdrawEvent {
-        disc: OreEvent::Withdraw as u64,
-        authority: *signer_info.key,
-        block_id: stake.block_id,
-        amount,
-        collateral: stake.collateral,
-        ts: clock.unix_timestamp,
-    }
-    .log_return();
+    program_log(
+        stake.block_id,
+        block_info.clone(),
+        &WithdrawEvent {
+            disc: OreEvent::Withdraw as u64,
+            authority: *signer_info.key,
+            block_id: stake.block_id,
+            amount,
+            collateral: stake.collateral,
+            ts: clock.unix_timestamp,
+        }
+        .to_bytes(),
+    )?;
 
     Ok(())
 }