diff --git a/api/src/state/proof.rs b/api/src/state/proof.rs
index 17f58ed..6db3c3a 100644
--- a/api/src/state/proof.rs
+++ b/api/src/state/proof.rs
@@ -19,11 +19,11 @@ pub struct Proof {
     /// The last hash the miner provided.
     pub last_hash: [u8; 32],
 
-    /// The last time this account provided a hash.
+    /// Timestamp of the last time this account provided a hash.
     pub last_hash_at: i64,
 
-    /// Buffer for possible future use.
-    pub _buffer: [u8; 8],
+    /// Timestamp of the last claim.
+    pub last_claim_at: i64,
 
     /// The keypair which has permission to submit hashes for mining.
     pub miner: Pubkey,
diff --git a/program/src/claim.rs b/program/src/claim.rs
index b98a970..29965f8 100644
--- a/program/src/claim.rs
+++ b/program/src/claim.rs
@@ -8,6 +8,7 @@ pub fn process_claim(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResult
     let amount = u64::from_le_bytes(args.amount);
 
     // Load accounts.
+    let clock = Clock::get()?;
     let [signer_info, beneficiary_info, proof_info, treasury_info, treasury_tokens_info, token_program] =
         accounts
     else {
@@ -34,6 +35,9 @@ pub fn process_claim(accounts: &[AccountInfo<'_>], data: &[u8]) -> ProgramResult
         .checked_sub(amount)
         .ok_or(OreError::ClaimTooLarge)?;
 
+    // Update last claim timestamp.
+    proof.last_claim_at = clock.unix_timestamp;
+
     // Transfer tokens from treasury to beneficiary.
     transfer_signed(
         treasury_info,