diff --git a/stacks-signer/CHANGELOG.md b/stacks-signer/CHANGELOG.md
index fd38fe9775..dc5507b065 100644
--- a/stacks-signer/CHANGELOG.md
+++ b/stacks-signer/CHANGELOG.md
@@ -11,6 +11,14 @@ and this project adheres to the versioning scheme outlined in the [README.md](RE
 
 ## Changed
 
+# [3.1.0.0.2.1]
+
+## Added
+
+## Changed
+
+- Prevent old reward cycle signers from processing block validation response messages that do not apply to blocks from their cycle.
+
 ## [3.1.0.0.2.0]
 
 ## Added
diff --git a/stacks-signer/src/v0/signer.rs b/stacks-signer/src/v0/signer.rs
index 22a02bc107..5bf8976784 100644
--- a/stacks-signer/src/v0/signer.rs
+++ b/stacks-signer/src/v0/signer.rs
@@ -564,6 +564,14 @@ impl Signer {
         // For mutability reasons, we need to take the block_info out of the map and add it back after processing
         let mut block_info = match self.signer_db.block_lookup(&signer_signature_hash) {
             Ok(Some(block_info)) => {
+                if block_info.reward_cycle != self.reward_cycle {
+                    // We are not signing for this reward cycle. Ignore the block.
+                    debug!(
+                        "{self}: Received a block validation response for a different reward cycle. Ignore it.";
+                        "requested_reward_cycle" => block_info.reward_cycle,
+                    );
+                    return None;
+                }
                 if block_info.is_locally_finalized() {
                     debug!("{self}: Received block validation for a block that is already marked as {}. Ignoring...", block_info.state);
                     return None;
@@ -635,6 +643,14 @@ impl Signer {
         }
         let mut block_info = match self.signer_db.block_lookup(&signer_signature_hash) {
             Ok(Some(block_info)) => {
+                if block_info.reward_cycle != self.reward_cycle {
+                    // We are not signing for this reward cycle. Ignore the block.
+                    debug!(
+                        "{self}: Received a block validation response for a different reward cycle. Ignore it.";
+                        "requested_reward_cycle" => block_info.reward_cycle,
+                    );
+                    return None;
+                }
                 if block_info.is_locally_finalized() {
                     debug!("{self}: Received block validation for a block that is already marked as {}. Ignoring...", block_info.state);
                     return None;