diff --git a/core/src/main/java/org/bitcoinj/core/NetworkParameters.java b/core/src/main/java/org/bitcoinj/core/NetworkParameters.java
index 8be5c36d..2dc8d8bf 100644
--- a/core/src/main/java/org/bitcoinj/core/NetworkParameters.java
+++ b/core/src/main/java/org/bitcoinj/core/NetworkParameters.java
@@ -107,7 +107,7 @@ public abstract class NetworkParameters {
     protected int[] addrSeeds;
     protected HttpDiscovery.Details[] httpSeeds = {};
     protected Map<Integer, Sha256Hash> checkpoints = new HashMap<>();
-    protected transient MessageSerializer defaultSerializer = null;
+    protected volatile transient MessageSerializer defaultSerializer = null;
 
     protected NetworkParameters() {
         alertSigningKey = SATOSHI_KEY;