diff --git a/pallets/drand/src/lib.rs b/pallets/drand/src/lib.rs
index 40bf7ccb9b..5695f1456d 100644
--- a/pallets/drand/src/lib.rs
+++ b/pallets/drand/src/lib.rs
@@ -292,6 +292,10 @@ pub mod pallet {
                     pulses_payload: payload,
                     signature,
                 } => {
+                    // Blacklist stale pulses in the txpool that can stall finalization.
+                    if payload.block_number < BlockNumberFor::<T>::from(5612500u32) {
+                        return InvalidTransaction::Stale.into();
+                    }
                     let signature = signature.as_ref().ok_or(InvalidTransaction::BadSigner)?;
                     Self::validate_signature_and_parameters(
                         payload,
diff --git a/pallets/drand/src/tests.rs b/pallets/drand/src/tests.rs
index e12653aebf..3f6470f04c 100644
--- a/pallets/drand/src/tests.rs
+++ b/pallets/drand/src/tests.rs
@@ -47,7 +47,7 @@ fn it_can_submit_valid_pulse_when_beacon_config_exists() {
         let p: Pulse = u_p.try_into_pulse().unwrap();
 
         let alice = sp_keyring::Sr25519Keyring::Alice;
-        let block_number = 1;
+        let block_number = 100_000_000;
         System::set_block_number(block_number);
 
         // Set the beacon config
@@ -91,7 +91,7 @@ fn it_can_submit_valid_pulse_when_beacon_config_exists() {
 fn it_rejects_invalid_pulse_due_to_bad_signature() {
     new_test_ext().execute_with(|| {
         let alice = sp_keyring::Sr25519Keyring::Alice;
-        let block_number = 1;
+		let block_number = 100_000_000;
         System::set_block_number(block_number);
 
         // Set the beacon config using Root origin
@@ -139,7 +139,7 @@ fn it_rejects_invalid_pulse_due_to_bad_signature() {
 #[test]
 fn it_rejects_pulses_with_non_incremental_round_numbers() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
 
@@ -189,7 +189,7 @@ fn it_rejects_pulses_with_non_incremental_round_numbers() {
 #[test]
 fn it_blocks_non_root_from_submit_beacon_info() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
 
@@ -239,7 +239,7 @@ fn it_blocks_non_root_from_submit_beacon_info() {
 #[test]
 fn signed_cannot_submit_beacon_info() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
 
@@ -268,7 +268,7 @@ fn signed_cannot_submit_beacon_info() {
 #[test]
 fn test_validate_unsigned_write_pulse() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
         let pulses_payload = PulsesPayload {
@@ -293,7 +293,7 @@ fn test_validate_unsigned_write_pulse() {
 #[test]
 fn test_not_validate_unsigned_write_pulse_with_bad_proof() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
         let pulses_payload = PulsesPayload {
@@ -319,7 +319,7 @@ fn test_not_validate_unsigned_write_pulse_with_bad_proof() {
 #[test]
 fn test_not_validate_unsigned_write_pulse_with_no_payload_signature() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
+        let block_number = 100_000_000;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
         let pulses_payload = PulsesPayload {
@@ -388,8 +388,8 @@ fn can_execute_and_handle_valid_http_responses() {
 #[test]
 fn validate_unsigned_rejects_future_block_number() {
     new_test_ext().execute_with(|| {
-        let block_number = 1;
-        let future_block_number = 100;
+        let block_number = 100_000_000;
+        let future_block_number = 100_000_100;
         let alice = sp_keyring::Sr25519Keyring::Alice;
         System::set_block_number(block_number);
         let pulses_payload = PulsesPayload {
diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs
index 193f585e3b..56b1d19268 100644
--- a/runtime/src/lib.rs
+++ b/runtime/src/lib.rs
@@ -207,7 +207,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
     //   `spec_version`, and `authoring_version` are the same between Wasm and native.
     // This value is set to 100 to notify Polkadot-JS App (https://polkadot.js.org/apps) to use
     //   the compatible custom types.
-    spec_version: 263,
+    spec_version: 264,
     impl_version: 1,
     apis: RUNTIME_API_VERSIONS,
     transaction_version: 1,