diff --git a/api/src/main/java/ai/djl/modality/cv/output/CategoryMask.java b/api/src/main/java/ai/djl/modality/cv/output/CategoryMask.java
index c0aea00b8f2..394a7461a5d 100644
--- a/api/src/main/java/ai/djl/modality/cv/output/CategoryMask.java
+++ b/api/src/main/java/ai/djl/modality/cv/output/CategoryMask.java
@@ -34,7 +34,9 @@ public class CategoryMask implements JsonSerializable {
 
     private static final int COLOR_BLACK = 0xFF000000;
 
+    @SuppressWarnings("serial")
     private List<String> classes;
+
     private int[][] mask;
 
     /**