diff --git a/go.mod b/go.mod
index 06e58f3..557b785 100644
--- a/go.mod
+++ b/go.mod
@@ -9,6 +9,7 @@ require (
 	github.com/pborman/getopt v1.1.0
 	github.com/rivo/uniseg v0.2.0 // indirect
 	github.com/yuin/gopher-lua v0.0.0-20200816102855-ee81675732da
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
 	golang.org/x/sys v0.0.0-20210521203332-0cec03c779c1 // indirect
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 	layeh.com/gopher-luar v1.0.8