diff --git a/ipn/ipnlocal/local.go b/ipn/ipnlocal/local.go
index d6daf3535..9e8886404 100644
--- a/ipn/ipnlocal/local.go
+++ b/ipn/ipnlocal/local.go
@@ -163,7 +163,7 @@ type watchSession struct {
 	ch        chan *ipn.Notify
 	owner     ipnauth.Actor // or nil
 	sessionID string
-	cancel    func() // call to signal that the session must be terminated
+	cancel    context.CancelFunc // to shut down the session
 }
 
 // LocalBackend is the glue between the major pieces of the Tailscale