diff --git a/src/main/java/org/qortal/crosschain/ElectrumX.java b/src/main/java/org/qortal/crosschain/ElectrumX.java
index ad211c03..0e70f787 100644
--- a/src/main/java/org/qortal/crosschain/ElectrumX.java
+++ b/src/main/java/org/qortal/crosschain/ElectrumX.java
@@ -142,7 +142,7 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 	private int nextId = 1;
 
 	private static final int TX_CACHE_SIZE = 1000;
-	@SuppressWarnings("serial")
+
 	private final Map<String, BitcoinyTransaction> transactionCache = Collections.synchronizedMap(new LinkedHashMap<>(TX_CACHE_SIZE + 1, 0.75F, true) {
 		// This method is called just after a new entry has been added
 		@Override
@@ -222,10 +222,10 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 		if (!(countObj instanceof Long) || !(hexObj instanceof String))
 			throw new ForeignBlockchainException.NetworkException("Missing/invalid 'count' or 'hex' entries in JSON from ElectrumX blockchain.block.headers RPC");
 
-		Long returnedCount = (Long) countObj;
+		long returnedCount = (Long) countObj;
 		String hex = (String) hexObj;
 
-		List<byte[]> rawBlockHeaders = new ArrayList<>(returnedCount.intValue());
+		List<byte[]> rawBlockHeaders = new ArrayList<>((int) returnedCount);
 
 		byte[] raw = HashCode.fromString(hex).asBytes();
 
@@ -592,7 +592,7 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 
 		Object peers = this.connectedRpc("server.peers.subscribe");
 
-		for (Object rawPeer : (JSONArray) peers) {
+		for (Object rawPeer : (JSONArray) Objects.requireNonNull(peers)) {
 			JSONArray peer = (JSONArray) rawPeer;
 			if (peer.size() < 3)
 				// We're expecting at least 3 fields for each peer entry: IP, hostname, features
@@ -721,7 +721,7 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 			// Check connection is suitable by asking for server features, including genesis block hash
 			JSONObject featuresJson = (JSONObject) this.connectedRpc("server.features");
 
-			if (featuresJson == null || Double.valueOf((String) featuresJson.get("protocol_min")) < MIN_PROTOCOL_VERSION)
+			if (featuresJson == null || Double.parseDouble((String) featuresJson.get("protocol_min")) < MIN_PROTOCOL_VERSION)
 				return Optional.of( recorder.recordConnection(server, requestedBy, true,  false, MINIMUM_VERSION_ERROR) );
 
 			if (this.expectedGenesisHash != null && !((String) featuresJson.get("genesis_hash")).equals(this.expectedGenesisHash))
@@ -729,9 +729,11 @@ public class ElectrumX extends BitcoinyBlockchainProvider {
 
 			// Ask for more servers
 			Set<Server> moreServers = serverPeersSubscribe();
+
 			// Discard duplicate servers we already know
 			moreServers.removeAll(this.servers);
-			// Add to both lists
+
+			// Add all servers to both lists
 			this.remainingServers.addAll(moreServers);
 			this.servers.addAll(moreServers);