diff --git a/src/pkg/flag/flag.go b/src/pkg/flag/flag.go
index 5444ad141c..3116dafb5a 100644
--- a/src/pkg/flag/flag.go
+++ b/src/pkg/flag/flag.go
@@ -33,7 +33,7 @@
 
 	After parsing, the arguments after the flag are available as the
 	slice flag.Args() or individually as flag.Arg(i).
-	The arguments are indexed from 0 up to flag.NArg().
+	The arguments are indexed from 0 through flag.NArg()-1.
 
 	Command line flag syntax:
 		-flag