diff --git a/README.md b/README.md
index d284c0cd..864633e6 100644
--- a/README.md
+++ b/README.md
@@ -67,6 +67,11 @@ To build and run the River UI locally for development:
    # This example is for Ubuntu and may be different on your system
    sudo apt-get install libssl-dev
 
+   # Install Node.js (v20+) and npm
+   # See https://nodejs.org/en/download for installation instructions.
+   # Note: system packages (e.g. `apt-get install npm`) may ship outdated
+   # versions that don't work — install from the official site instead.
+
    # Install build tools
    cargo install dioxus-cli
    cargo install cargo-make
@@ -85,6 +90,9 @@ To build and run the River UI locally for development:
    git submodule init
    git submodule update
 
+   # Install Node.js dependencies (Tailwind CSS)
+   cd ui && npm install && cd ..
+
    # Run development server with example data
    cargo make dev-example
    ```
diff --git a/ui/src/components/app/freenet_api/room_synchronizer.rs b/ui/src/components/app/freenet_api/room_synchronizer.rs
index 90a4c567..1641d16a 100644
--- a/ui/src/components/app/freenet_api/room_synchronizer.rs
+++ b/ui/src/components/app/freenet_api/room_synchronizer.rs
@@ -493,10 +493,11 @@ impl RoomSynchronizer {
                             let authorized_upgrade =
                                 AuthorizedUpgradeV1::new(upgrade, &room_data.self_sk);
 
-                            ChatRoomStateV1 {
-                                upgrade: OptionalUpgradeV1(Some(authorized_upgrade)),
-                                ..Default::default()
-                            }
+                            // Clone the current room state so the old contract's
+                            // validation passes, then set the upgrade pointer on it.
+                            let mut state = room_data.room_state.clone();
+                            state.upgrade = OptionalUpgradeV1(Some(authorized_upgrade));
+                            state
                         } else {
                             continue;
                         }