diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2aa6319..215ab18 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -29,8 +29,6 @@ env:
   CURL_CACHE_DIR: ~/.cache/curl
   IMAGE_NAME: cisagov/example
   PIP_CACHE_DIR: ~/.cache/pip
-  PLATFORMS: "linux/amd64,linux/arm/v6,linux/arm/v7,\
-  linux/arm64,linux/ppc64le,linux/s390x"
   PRE_COMMIT_CACHE_DIR: ~/.cache/pre-commit
   RUN_TMATE: ${{ secrets.RUN_TMATE }}
 
@@ -347,15 +345,24 @@ jobs:
         uses: mxschmitt/action-tmate@v3
         if: env.RUN_TMATE
   build-push-all:
-    # Builds the final set of images for each of the platforms listed in
-    # PLATFORMS environment variable.  These images are tagged with the Docker
-    # tags calculated in the "prepare" job and pushed to Docker Hub and the
-    # GitHub Container Registry.  The contents of README.md are pushed as the
+    # Builds the final set of images for each of the platforms listed
+    # below.  These images are tagged with the Docker tags calculated
+    # in the "prepare" job and pushed to Docker Hub and the GitHub
+    # Container Registry.  The contents of README.md are pushed as the
     # image's description to Docker Hub.  This job is skipped when the
     # triggering event is a pull request.
     name: "Build and push all platforms"
     runs-on: ubuntu-latest
     needs: [lint, prepare, test]
+    strategy:
+      matrix:
+        platform:
+          - linux/amd64
+          - linux/arm/v6
+          - linux/arm/v7
+          - linux/arm64
+          - linux/ppc64le
+          - linux/s390x
     if: github.event_name != 'pull_request'
     steps:
       - name: Login to Docker Hub
@@ -396,7 +403,7 @@ jobs:
           cache-to: type=local,dest=${{ env.BUILDX_CACHE_DIR }}
           context: .
           file: ./Dockerfile-x
-          platforms: ${{ env.PLATFORMS }}
+          platforms: ${{ matrix.platform }}
           push: true
           tags: ${{ needs.prepare.outputs.tags }}
           # For a list of pre-defined annotation keys and value types see: