diff --git a/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java b/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
index 18f93b0e3f..761695fc56 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/Transaction.java
@@ -473,7 +473,7 @@ public byte[] getEncodedRaw() {
         return rlpRaw;
     }
 
-    public byte[] getEncoded() {
+    public synchronized byte[] getEncoded() {
 
         if (rlpEncoded != null) return rlpEncoded;