diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 86ba83cf..ef6dbe94 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -1,6 +1,13 @@
 name: Publish Docker image
 
 on:
+  workflow_dispatch:
+    inputs:
+      ref:
+        description: 'Git ref (tag or commit SHA) to build'
+        required: true
+        type: string 
+        default: 'main'
   push:
     tags:
       - 'v*'
@@ -33,6 +40,8 @@ jobs:
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.inputs.ref || github.ref }}
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
diff --git a/Dockerfile b/Dockerfile
index aeb8aaa0..ff2d8d30 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -21,7 +21,7 @@ ENV RAILS_ENV="production" \
 FROM base AS build
 
 # Install packages needed to build gems
-RUN apt-get install --no-install-recommends -y build-essential libpq-dev pkg-config
+RUN apt-get install --no-install-recommends -y build-essential libpq-dev git pkg-config
 
 # Install application gems
 COPY .ruby-version Gemfile Gemfile.lock ./