diff --git a/opensearch/client.go b/opensearch/client.go
index 49e0f6f..89d38bf 100644
--- a/opensearch/client.go
+++ b/opensearch/client.go
@@ -89,6 +89,7 @@ func (b *stringSliceReader) Read(p []byte) (n int, err error) {
 		copy(p, sbt)
 		p = p[len(sbt):]
 		b.pointer++
+		n += len(sbt)
 		err = nil
 	}
 	err = io.EOF