diff --git a/.github/workflows/reviewer.yml b/.github/workflows/reviewer.yml
index 902ecc6..0161ca2 100644
--- a/.github/workflows/reviewer.yml
+++ b/.github/workflows/reviewer.yml
@@ -23,7 +23,8 @@ jobs:
         with:
           python-version: "3.12"
       - name: Install umbra-reviewer
-        run: pip install "umbra-reviewer>=0.1.0"
+        # source-available (All Rights Reserved); install from source, not PyPI.
+        run: pip install "umbra-reviewer @ git+https://github.com/bkd-dotcom/umbra-reviewer@v0.1.0"
       - name: Compute the PR diff
         env:
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
diff --git a/README.md b/README.md
index a92d123..291acfe 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ with [umbra-core](https://github.com/bkd-dotcom/umbra-core).
 ## Prerequisite
 
 ```bash
-pip install "umbra-core>=0.5.0"
+pip install "umbra-core @ git+https://github.com/bkd-dotcom/umbra-core@v0.5.3"
 ```
 
 Add a `.umbra/admission.yaml` to your repo (allowed/forbidden paths, diff budget,
diff --git a/config.toml b/config.toml
index fd9ff42..0881be1 100644
--- a/config.toml
+++ b/config.toml
@@ -1,5 +1,5 @@
 # Umbra MCP server for Codex — add to ~/.codex/config.toml
-# Requires: pip install "umbra-core>=0.2.0"
+# Requires: pip install "umbra-core @ git+https://github.com/bkd-dotcom/umbra-core@v0.5.3"
 
 [mcp_servers.umbra]
 command = "python"