diff --git a/src/main/java/codes/thischwa/cf/JsonConf.java b/src/main/java/codes/thischwa/cf/JsonConf.java
index e2e7a4a..c9ebbd7 100644
--- a/src/main/java/codes/thischwa/cf/JsonConf.java
+++ b/src/main/java/codes/thischwa/cf/JsonConf.java
@@ -18,7 +18,7 @@ class JsonConf {
   static ObjectMapper initObjectMapper() {
     ObjectMapper mapper = new ObjectMapper();
     mapper.registerModule(new JavaTimeModule());
-    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
+    mapper.setDefaultPropertyInclusion(JsonInclude.Include.NON_NULL);
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
     mapper.setPropertyNamingStrategy(PropertyNamingStrategies.SNAKE_CASE);
     return mapper;