diff --git a/location4j/src/main/java/com/tomaytotomato/model/City.java b/location4j/src/main/java/com/tomaytotomato/model/City.java
index d6daf67..c2404e0 100644
--- a/location4j/src/main/java/com/tomaytotomato/model/City.java
+++ b/location4j/src/main/java/com/tomaytotomato/model/City.java
@@ -1,5 +1,6 @@
 package com.tomaytotomato.model;
 
+import java.io.Serial;
 import java.io.Serializable;
 import java.math.BigDecimal;
 import java.util.Objects;
@@ -14,6 +15,7 @@
  */
 public class City implements Serializable {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   private Integer id;
diff --git a/location4j/src/main/java/com/tomaytotomato/model/Country.java b/location4j/src/main/java/com/tomaytotomato/model/Country.java
index 52f3e20..fc05f82 100644
--- a/location4j/src/main/java/com/tomaytotomato/model/Country.java
+++ b/location4j/src/main/java/com/tomaytotomato/model/Country.java
@@ -1,5 +1,6 @@
 package com.tomaytotomato.model;
 
+import java.io.Serial;
 import java.io.Serializable;
 import java.math.BigDecimal;
 import java.util.List;
@@ -15,6 +16,7 @@
  */
 public class Country implements Serializable {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   private Integer id;
diff --git a/location4j/src/main/java/com/tomaytotomato/model/State.java b/location4j/src/main/java/com/tomaytotomato/model/State.java
index c41d6f8..c3c2983 100644
--- a/location4j/src/main/java/com/tomaytotomato/model/State.java
+++ b/location4j/src/main/java/com/tomaytotomato/model/State.java
@@ -1,5 +1,6 @@
 package com.tomaytotomato.model;
 
+import java.io.Serial;
 import java.io.Serializable;
 import java.math.BigDecimal;
 import java.util.List;
@@ -15,6 +16,7 @@
  */
 public class State implements Serializable {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   private Integer id;
diff --git a/location4j/src/main/java/com/tomaytotomato/model/TimeZone.java b/location4j/src/main/java/com/tomaytotomato/model/TimeZone.java
index 729c6ba..09f27e1 100644
--- a/location4j/src/main/java/com/tomaytotomato/model/TimeZone.java
+++ b/location4j/src/main/java/com/tomaytotomato/model/TimeZone.java
@@ -1,5 +1,6 @@
 package com.tomaytotomato.model;
 
+import java.io.Serial;
 import java.io.Serializable;
 import java.util.Objects;
 import javax.annotation.processing.Generated;
@@ -13,6 +14,7 @@
  */
 public class TimeZone implements Serializable {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   private String zoneName;