diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..e7eec8a
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module github.com/xtaci/smux
+
+go 1.13
+
+require github.com/pkg/errors v0.8.1