diff --git a/.github/workflows/ci-subaction.yml b/.github/workflows/ci-subaction.yml
index 0a9e85a..d881092 100644
--- a/.github/workflows/ci-subaction.yml
+++ b/.github/workflows/ci-subaction.yml
@@ -25,8 +25,15 @@ on:
       - 'test/**'
 
 jobs:
-  list-targets-group:
+  list-targets:
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - testdir: group
+          - testdir: group-matrix
+            target: validate
     steps:
       -
         name: Checkout
@@ -36,14 +43,26 @@ jobs:
         id: gen
         uses: ./subaction/list-targets
         with:
-          workdir: ./test/group
-      -
-        name: Show matrix
-        run: |
-          echo matrix=${{ steps.gen.outputs.matrix }}
+          workdir: ./test/${{ matrix.testdir }}
+          target: ${{ matrix.target }}
 
-  list-targets-group-matrix:
+  matrix:
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - testdir: group
+          - testdir: group-matrix
+            target: validate
+          - testdir: group-with-platform
+            target: validate
+          - testdir: group-with-platform
+            target: validate
+            fields: platforms
+          - testdir: group-with-platform
+            target: validate
+            fields: platforms,dockerfile
     steps:
       -
         name: Checkout
@@ -51,11 +70,8 @@ jobs:
       -
         name: Matrix gen
         id: gen
-        uses: ./subaction/list-targets
+        uses: ./subaction/matrix
         with:
-          workdir: ./test/group-matrix
-          target: validate
-      -
-        name: Show matrix
-        run: |
-          echo matrix=${{ steps.gen.outputs.matrix }}
+          workdir: ./test/${{ matrix.testdir }}
+          target: ${{ matrix.target }}
+          fields: ${{ matrix.fields }}
diff --git a/subaction/matrix/action.yml b/subaction/matrix/action.yml
new file mode 100644
index 0000000..76a62b9
--- /dev/null
+++ b/subaction/matrix/action.yml
@@ -0,0 +1,98 @@
+# https://docs.github.com/en/actions/creating-actions/metadata-syntax-for-github-actions
+name: 'Matrix'
+description: 'Generate a matrix from a Bake definition to help distributing builds in your workflow'
+
+inputs:
+  workdir:
+    description: Working directory
+    default: '.'
+    required: false
+  files:
+    description: List of Bake files
+    required: false
+  target:
+    description: Bake target
+    required: false
+  fields:
+    description: Comma separated list of extra fields to include in the matrix
+    required: false
+
+outputs:
+  matrix:
+    description: List of includes as matrix
+    value: ${{ steps.generate.outputs.includes }}
+
+runs:
+  using: composite
+  steps:
+    -
+      name: Generate
+      id: generate
+      uses: actions/github-script@v7
+      with:
+        script: |
+          let def;
+          const files = `${{ inputs.files }}` ? `${{ inputs.files }}`.split('\n') : [];
+          const target = `${{ inputs.target }}`;
+          const fields = `${{ inputs.fields }}` ? `${{ inputs.fields }}`.split(',') : [];
+
+          await core.group(`Parsing definition`, async () => {
+            let args = ['buildx', 'bake'];
+            for (const file of files) {
+              args.push('--file', file);
+            }
+            if (target) {
+              args.push(target);
+            }
+            args.push('--print');
+
+            const res = await exec.getExecOutput('docker', args, {
+              ignoreReturnCode: true,
+              silent: true,
+              cwd: `${{ inputs.workdir }}`
+            });
+            if (res.stderr.length > 0 && res.exitCode != 0) {
+              throw new Error(res.stderr);
+            }
+            def = JSON.parse(res.stdout.trim());
+            core.info(JSON.stringify(def, null, 2));
+          });
+
+          await core.group(`Generating matrix`, async () => {
+            let includes = [];
+            for (const targetName of Object.keys(def.target)) {
+              const target = def.target[targetName];
+              if (fields.length > 0) {
+                let hasFields = false;
+                fields.forEach(field => {
+                  if (target[field]) {
+                    hasFields = true;
+                    if (Array.isArray(target[field])) {
+                      target[field].forEach(value => {
+                        const include = { target: targetName };
+                        include[field] = value;
+                        includes.push(include);
+                      });
+                    } else {
+                      const include = { target: targetName };
+                      include[field] = target[field];
+                      includes.push(include);
+                    }
+                  } else {
+                    core.warning(`Field "${field}" not found in target ${targetName}`);
+                  }
+                });
+                if (!hasFields) {
+                  includes.push({
+                    target: targetName
+                  });
+                }
+              } else {
+                includes.push({
+                  target: targetName
+                });
+              }
+            }
+            core.info(JSON.stringify(includes, null, 2));
+            core.setOutput('includes', JSON.stringify(includes));
+          });
diff --git a/test/group-with-platform/docker-bake.hcl b/test/group-with-platform/docker-bake.hcl
new file mode 100644
index 0000000..bfba830
--- /dev/null
+++ b/test/group-with-platform/docker-bake.hcl
@@ -0,0 +1,36 @@
+group "validate" {
+  targets = ["lint", "lint-gopls", "validate-vendor", "validate-docs"]
+}
+
+target "lint" {
+  dockerfile = "./hack/dockerfiles/lint.Dockerfile"
+  output = ["type=cacheonly"]
+  platforms = [
+    "darwin/amd64",
+    "darwin/arm64",
+    "linux/amd64",
+    "linux/arm64",
+    "linux/s390x",
+    "linux/ppc64le",
+    "linux/riscv64",
+    "windows/amd64",
+    "windows/arm64"
+  ]
+}
+
+target "lint-gopls" {
+  inherits = ["lint"]
+  target = "gopls-analyze"
+}
+
+target "validate-vendor" {
+  dockerfile = "./hack/dockerfiles/vendor.Dockerfile"
+  target = "validate"
+  output = ["type=cacheonly"]
+}
+
+target "validate-docs" {
+  dockerfile = "./hack/dockerfiles/docs.Dockerfile"
+  target = "validate"
+  output = ["type=cacheonly"]
+}