diff --git a/.github/workflows/mypy_primer.yml b/.github/workflows/mypy_primer.yml
index baff7b76337b..fc57eb277c75 100644
--- a/.github/workflows/mypy_primer.yml
+++ b/.github/workflows/mypy_primer.yml
@@ -48,10 +48,48 @@ jobs:
             --num-shards 3 --shard-index ${{ matrix.shard-index }} \
             --debug \
             --output concise \
-            | tee diff.txt
+            | tee diff_${{ matrix.shard-index }}.txt
           ) || [ $? -eq 1 ]
       - name: Upload mypy_primer diff
         uses: actions/upload-artifact@v2
         with:
-          name: mypy_primer_diff_${{ matrix.shard-index }}
-          path: diff.txt
+          name: mypy_primer_diffs
+          path: diff_${{ matrix.shard-index }}.txt
+
+  comment:
+    name: Comment
+    runs-on: ubuntu-latest
+    needs: mypy_primer
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Download diffs
+        uses: actions/download-artifact@v2
+        with:
+          name: mypy_primer_diffs
+
+      - name: Post comment
+        uses: actions/github-script@v3
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            const fs = require('fs')
+            const data = (
+              ['diff_0.txt', 'diff_1.txt']
+              .map(fileName => fs.readFileSync(fileName, { encoding: 'utf8' }))
+              .join('')
+              .substr(0, 30000)  // About 300 lines
+            )
+
+            console.log("Diff from mypy_primer:")
+            console.log(data)
+
+            if (data.trim()) {
+              const body = 'Diff from [mypy_primer](https://github.com/hauntsaninja/mypy_primer), showing the effect of this PR on open source code:\n```diff\n' + data + '```'
+              await github.issues.createComment({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                body
+              })
+            }
diff --git a/.github/workflows/mypy_primer_comment.yml b/.github/workflows/mypy_primer_comment.yml
deleted file mode 100644
index 0fd646d6ce5b..000000000000
--- a/.github/workflows/mypy_primer_comment.yml
+++ /dev/null
@@ -1,104 +0,0 @@
-name: Comment with mypy_primer diff
-
-on:
-  # pull_request_target gives us access to a write token which we need to post a comment
-  # The presence of a write token means that we can't run any untrusted code (i.e. malicious PRs),
-  # which is why this its own workflow. Github Actions doesn't make it easy for workflows to talk to
-  # each other, so the approach here is to poll for workflow runs, find the mypy_primer run for our
-  # commit, wait till it's completed, and download and post the diff.
-  pull_request_target:
-    paths-ignore:
-    - 'docs/**'
-    - '**/*.rst'
-    - '**/*.md'
-    - 'mypyc/**'
-
-jobs:
-  mypy_primer:
-    name: Comment
-    runs-on: ubuntu-latest
-    steps:
-      - name: Install dependencies
-        run: npm install adm-zip
-      - name: Post comment
-        uses: actions/github-script@v3
-        with:
-          github-token: ${{secrets.GITHUB_TOKEN}}
-          script: |
-            const AdmZip = require(`${process.env.GITHUB_WORKSPACE}/node_modules/adm-zip`)
-
-            // Because of pull_request_target, context.sha is the PR base branch
-            // So we need to ask Github for the SHA of the PR's head commit
-            const pull_request = await github.pulls.get({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                pull_number: context.issue.number,
-            })
-            const pr_commit_sha = pull_request.data.head.sha
-            console.log("Looking for mypy_primer run for commit:", pr_commit_sha)
-
-            // Find the mypy_primer run for our commit and wait till it's completed
-            // We wait up to an hour before timing out
-            async function check_mypy_primer() {
-              // We're only looking at the first page, so in theory if we open enough PRs around
-              // the same time, this will fail to find the run.
-              const response = await github.actions.listWorkflowRuns({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                workflow_id: "mypy_primer.yml",
-              })
-              if (response) {
-                return response.data.workflow_runs.find(run => run.head_sha == pr_commit_sha)
-              }
-              return undefined
-            }
-
-            const end_time = Number(new Date()) + 60 * 60 * 1000
-            let primer_run = await check_mypy_primer()
-            while (!primer_run || primer_run.status != "completed") {
-              if (Number(new Date()) > end_time) {
-                throw Error("Timed out waiting for mypy_primer")
-              }
-              console.log("Waiting for mypy_primer to complete...")
-              await new Promise(r => setTimeout(r, 10000))
-              primer_run = await check_mypy_primer()
-            }
-            console.log("Found mypy_primer run!")
-            console.log(primer_run)
-
-            // Download artifact(s) from the run
-            const artifacts = await github.actions.listWorkflowRunArtifacts({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                run_id: primer_run.id,
-            })
-            const filtered_artifacts = artifacts.data.artifacts.filter(
-              a => a.name.startsWith("mypy_primer_diff")
-            )
-            console.log("Artifacts from mypy_primer:")
-            console.log(filtered_artifacts)
-
-            async function get_artifact_data(artifact) {
-              const zip = await github.actions.downloadArtifact({
-                  owner: context.repo.owner,
-                  repo: context.repo.repo,
-                  artifact_id: artifact.id,
-                  archive_format: "zip",
-              })
-              const adm = new AdmZip(Buffer.from(zip.data))
-              return adm.readAsText(adm.getEntry("diff.txt"))
-            }
-
-            const all_data = await Promise.all(filtered_artifacts.map(get_artifact_data))
-            const data = all_data.join("\n")
-
-            console.log("Diff from mypy_primer:")
-            console.log(data)
-            if (data.trim()) {
-              await github.issues.createComment({
-                issue_number: context.issue.number,
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                body: 'Diff from [mypy_primer](https://github.com/hauntsaninja/mypy_primer), showing the effect of this PR on open source code:\n```diff\n' + data + '```'
-              })
-            }