diff --git a/docs/walkthrough.rst b/docs/walkthrough.rst
index b7da1ab..704015d 100644
--- a/docs/walkthrough.rst
+++ b/docs/walkthrough.rst
@@ -78,7 +78,7 @@ implicitly has access to a no-op (doing nothing).
 .. note::
 
    Only include actions that the game actually responds to. Listing
-   unreachable keys wastes part of the agent's action space and may slow
+   unused keys wastes part of the agent's action space and may slow
    training.
 
 ``reward``