diff --git a/crates/iroha/tests/integration/extra_functional/connected_peers.rs b/crates/iroha/tests/integration/extra_functional/connected_peers.rs
index 4bc748200d3..3c6f63c6b39 100644
--- a/crates/iroha/tests/integration/extra_functional/connected_peers.rs
+++ b/crates/iroha/tests/integration/extra_functional/connected_peers.rs
@@ -118,6 +118,31 @@ fn connected_peers_with_f(faults: u64, start_port: Option<u16>) -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn unregister_single_peer() -> Result<()> {
+    let (_rt, network, _) = Network::start_test_with_runtime(7, None);
+    wait_for_genesis_committed(&network.clients(), 0);
+
+    let peer_clients: Vec<_> = Network::peers(&network)
+        .zip(Network::clients(&network))
+        .collect();
+
+    // Unregister a peer
+    let removed_peer_idx = rand::thread_rng().gen_range(0..peer_clients.len());
+    let (removed_peer, _) = &peer_clients[removed_peer_idx];
+    let unregister_peer = Unregister::peer(removed_peer.id.clone());
+    peer_clients
+        .choose(&mut thread_rng())
+        .unwrap()
+        .1
+        .submit_blocking(unregister_peer)?;
+
+    let pipeline_time = Config::pipeline_time();
+
+    thread::sleep(pipeline_time * 2);
+    Ok(())
+}
+
 fn check_status(peer_clients: &[(&Peer, Client)], expected_blocks: u64) {
     let n_peers = peer_clients.len() as u64;
 
diff --git a/crates/iroha_core/src/sumeragi/main_loop.rs b/crates/iroha_core/src/sumeragi/main_loop.rs
index 2cdf071d362..5802cafe188 100644
--- a/crates/iroha_core/src/sumeragi/main_loop.rs
+++ b/crates/iroha_core/src/sumeragi/main_loop.rs
@@ -628,6 +628,16 @@ impl Sumeragi {
                 );
 
                 if let Ok(signatory_idx) = usize::try_from(signature.0) {
+                    if signatory_idx >= self.topology.as_ref().len() {
+                        error!(
+                            peer_id=%self.peer_id,
+                            role=%self.role(),
+                            ?signatory_idx,
+                            topology_size=%self.topology.as_ref().len(),
+                            "Signature index is out of range."
+                        );
+                        return;
+                    }
                     let signatory = &self.topology.as_ref()[signatory_idx];
 
                     match self.topology.role(signatory) {
diff --git a/crates/iroha_p2p/src/network.rs b/crates/iroha_p2p/src/network.rs
index fedded056b9..2716f862f15 100644
--- a/crates/iroha_p2p/src/network.rs
+++ b/crates/iroha_p2p/src/network.rs
@@ -219,7 +219,7 @@ impl<T: Pload, K: Kex, E: Enc> NetworkBase<T, K, E> {
     #[log(skip(self), fields(listen_addr=%self.listen_addr, public_key=%self.key_pair.public_key()))]
     async fn run(mut self) {
         // TODO: probably should be configuration parameter
-        let mut update_topology_interval = tokio::time::interval(Duration::from_millis(100));
+        let mut update_topology_interval = tokio::time::interval(Duration::from_millis(1000));
         loop {
             tokio::select! {
                 // Select is biased because we want to service messages to take priority over data messages.