diff --git a/src/main/java/io/orkes/conductor/client/ApiClient.java b/src/main/java/io/orkes/conductor/client/ApiClient.java
index c68be7cf..f32832e8 100644
--- a/src/main/java/io/orkes/conductor/client/ApiClient.java
+++ b/src/main/java/io/orkes/conductor/client/ApiClient.java
@@ -37,6 +37,8 @@
 
 import javax.net.ssl.*;
 
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.threeten.bp.LocalDate;
@@ -97,6 +99,8 @@ public ApiClient(String basePath) {
         httpClient = new OkHttpClient();
         verifyingSsl = true;
         json = new JSON();
+        GsonBuilder builder = new GsonBuilder().serializeNulls();
+        json.setGson(builder.create());
         authentications = new HashMap<String, Authentication>();
     }