diff --git a/pkg/wrapper/nmt_wrapper.go b/pkg/wrapper/nmt_wrapper.go
index c57019cfad..01499b94d7 100644
--- a/pkg/wrapper/nmt_wrapper.go
+++ b/pkg/wrapper/nmt_wrapper.go
@@ -28,8 +28,10 @@ type ErasuredNamespacedMerkleTree struct {
 	// axisIndex is the index of the axis that this tree is on. This is passed
 	// by rsmt2d and used to help determine which quadrant each leaf belongs to.
 	axisIndex uint64
-	// shareIndex is the index of the share that is being pushed to the tree. It
-	// is used to help determine which quadrant each leaf belongs to.
+	// shareIndex is the index of the share in a row or column that is being
+	// pushed to the tree. It is expected to be in the range: 0 <= shareIndex <
+	// 2*squareSize. shareIndex is used to help determine which quadrant each
+	// leaf belongs to.
 	shareIndex uint64
 }