diff --git a/README.md b/README.md
index 72eba1f..b401f2b 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,9 @@
 # Tea
 
-茶! The fun, functional way to build terminal apps. A Go framework based on
-[The Elm Architecture][elm].
+The fun, functional way to build terminal apps. A Go framework based on
+[The Elm Architecture][elm]. 茶!
+
+⚠️  This project is a pre-release! The API is subject to change a little.
 
 ## Simple example
 
diff --git a/tea.go b/tea.go
index cfeb5f0..08db553 100644
--- a/tea.go
+++ b/tea.go
@@ -1,6 +1,7 @@
 package tea
 
 import (
+	"context"
 	"errors"
 	"io"
 	"os"
@@ -18,7 +19,7 @@ type Cmd func(Model) Msg
 
 // Sub is an event subscription. If it returns nil it's considered a no-op,
 // but there's really no reason to have a nil subscription.
-type Sub func(Model) Msg
+type Sub func(context.Context, Model) Msg
 
 // Subs is a keyed set of subscriptions. The key should be a unique
 // identifier; two different subscriptions should not have the same key