diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index fca06eede2..0a3945fb45 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -7,6 +7,7 @@ on:
     tags: ["v*"]
     branches: [ master, main, develop ]
   workflow_dispatch:
+  pull_request:
 
 permissions:
   contents: read
@@ -40,7 +41,7 @@ jobs:
         # https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepsshell
         shell: bash
         run: |
-          echo "SYNAPSE_VERSION=$(grep "^version" pyproject.toml | sed -E 's/version\s*=\s*["]([^"]*)["]/\1/')" >> $GITHUB_ENV
+          echo "SYNAPSE_VERSION=0.0.0" >> $GITHUB_ENV
 
       - name: Log in to DockerHub
         uses: docker/login-action@v3
@@ -60,14 +61,11 @@ jobs:
         uses: docker/metadata-action@master
         with:
           images: |
-            docker.io/matrixdotorg/synapse
             ghcr.io/element-hq/synapse
           flavor: |
             latest=false
           tags: |
-            type=raw,value=develop,enable=${{ github.ref == 'refs/heads/develop' }}
-            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/master' }}
-            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' }}
+            type=raw,value=test-cosign
             type=pep440,pattern={{raw}}
 
       - name: Build and push all platforms
@@ -77,7 +75,6 @@ jobs:
           push: true
           labels: |
             gitsha1=${{ github.sha }}
-            org.opencontainers.image.version=${{ env.SYNAPSE_VERSION }}
           tags: "${{ steps.set-tag.outputs.tags }}"
           file: "docker/Dockerfile"
           platforms: linux/amd64,linux/arm64