diff --git a/internal/storage/payload.go b/internal/storage/payload.go
index 52fe76f6fc..57110c4503 100644
--- a/internal/storage/payload.go
+++ b/internal/storage/payload.go
@@ -75,11 +75,13 @@ type PayloadReaderInterface interface {
 	Close()
 }
 
+// PayloadWriter writes data into payload
 type PayloadWriter struct {
 	payloadWriterPtr C.CPayloadWriter
 	colType          schemapb.DataType
 }
 
+// PayloadReader reads data from payload
 type PayloadReader struct {
 	payloadReaderPtr C.CPayloadReader
 	colType          schemapb.DataType