diff --git a/infrastructure/kzg/src/main/java/tech/pegasys/teku/kzg/ckzg4844/CKZG4844.java b/infrastructure/kzg/src/main/java/tech/pegasys/teku/kzg/ckzg4844/CKZG4844.java
index fcc30ed704d..51d430e03c4 100644
--- a/infrastructure/kzg/src/main/java/tech/pegasys/teku/kzg/ckzg4844/CKZG4844.java
+++ b/infrastructure/kzg/src/main/java/tech/pegasys/teku/kzg/ckzg4844/CKZG4844.java
@@ -87,7 +87,7 @@ public synchronized void loadTrustedSetup(final String trustedSetupFile) throws
   }
 
   @Override
-  public void freeTrustedSetup() throws KZGException {
+  public synchronized void freeTrustedSetup() throws KZGException {
     try {
       CKZG4844JNI.freeTrustedSetup();
       loadedTrustedSetupFile = Optional.empty();