diff --git a/impl/model/src/main/java/io/serverlessworkflow/impl/model/jackson/JacksonModel.java b/impl/model/src/main/java/io/serverlessworkflow/impl/model/jackson/JacksonModel.java
index aae12ba9b..df55437bf 100644
--- a/impl/model/src/main/java/io/serverlessworkflow/impl/model/jackson/JacksonModel.java
+++ b/impl/model/src/main/java/io/serverlessworkflow/impl/model/jackson/JacksonModel.java
@@ -15,6 +15,7 @@
  */
 package io.serverlessworkflow.impl.model.jackson;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
@@ -48,6 +49,7 @@ protected JacksonModel(JsonNode node) {
   }
 
   @Override
+  @JsonIgnore
   public boolean isNull() {
     return node.isNull();
   }