diff --git a/metropolis/handbook/src/ch03-00-cluster-architecture.md b/metropolis/handbook/src/ch03-00-cluster-architecture.md
index 9f5669c..68c9384 100644
--- a/metropolis/handbook/src/ch03-00-cluster-architecture.md
+++ b/metropolis/handbook/src/ch03-00-cluster-architecture.md
@@ -54,7 +54,7 @@
 '-------------------'           | Seals/Unseals
          | Mounts               v
          |           .---------------------.        .------------------------.
-         | .---------| Node Encryption Key |        |    Running Cluster     |
+         | .---------|   Node Unlock Key   |        |    Running Cluster     |
          |/          '---------------------'        |------------------------|
          | .----------------------------------------| Cluster Encryption Key |
          |/                                         |       (per node)       |