diff --git a/container/mts/payload.go b/container/mts/payload.go
index ee6f0190..2d6b2bbd 100644
--- a/container/mts/payload.go
+++ b/container/mts/payload.go
@@ -155,7 +155,7 @@ var (
 	errPTSRange      = errors.New("PTS interval invalid")
 )
 
-// TrimToPTSRange returns the sub Clip in PTS range defined by from and to.
+// TrimToPTSRange returns the sub Clip in a PTS range defined by from and to.
 // The first Frame in the new Clip will be the Frame for which from corresponds
 // exactly with Frame.PTS, or the Frame in which from lies within. The final
 // Frame in the Clip will be the previous of that for which to coincides with,