diff --git a/src/test/java/org/opensearch/knn/index/codec/KNNCodecTestCase.java b/src/test/java/org/opensearch/knn/index/codec/KNNCodecTestCase.java
index c9a1900b5..6bfde31bb 100644
--- a/src/test/java/org/opensearch/knn/index/codec/KNNCodecTestCase.java
+++ b/src/test/java/org/opensearch/knn/index/codec/KNNCodecTestCase.java
@@ -122,6 +122,7 @@ public void testMultiFieldsKnnIndex(Codec codec) throws Exception {
         IndexWriterConfig iwc = newIndexWriterConfig();
         iwc.setMergeScheduler(new SerialMergeScheduler());
         iwc.setCodec(codec);
+        // Set merge policy to no merges so that we create a predictable number of segments.
         iwc.setMergePolicy(NoMergePolicy.INSTANCE);
 
         /**