diff --git a/.github/main.workflow b/.github/main.workflow
index b1b61554f9..4ff7845b9d 100644
--- a/.github/main.workflow
+++ b/.github/main.workflow
@@ -1,16 +1,10 @@
 workflow "Build & Release Manifest" {
   on = "push"
-  resolves = ["tag-master"]
+  resolves = ["manifest-build-and-tag"]
 }
 
-action "build-manifest" {
+action "manifest-build-and-tag" {
   uses = "./tools/docker/github"
-  runs = ["bash", "-c", "tools/ci/action_manifest_build.sh"]
-}
-
-action "tag-master" {
-  needs = "build-manifest"
-  uses = "./tools/docker/github"
-  runs = ["python", "tools/ci/tag_master.py"]
+  runs = ["python", "tools/ci/manifest_build.py"]
   secrets = ["GITHUB_TOKEN"]
 }
diff --git a/tools/ci/action_manifest_build.sh b/tools/ci/action_manifest_build.sh
deleted file mode 100755
index ad6a4cb16e..0000000000
--- a/tools/ci/action_manifest_build.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/bin/bash
-set -ex
-
-mkdir -p ~/meta
-
-WPT_MANIFEST_FILE=~/meta/MANIFEST.json
-
-./wpt manifest -p $WPT_MANIFEST_FILE
-gzip -k -f --best $WPT_MANIFEST_FILE
-bzip2 -k -f --best $WPT_MANIFEST_FILE
-zstd -k -f --ultra -22 $WPT_MANIFEST_FILE
diff --git a/tools/ci/ci_manifest.sh b/tools/ci/ci_manifest.sh
deleted file mode 100755
index 7d0d5ca041..0000000000
--- a/tools/ci/ci_manifest.sh
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/bin/bash
-set -ex
-
-SCRIPT_DIR=$(cd $(dirname "$0") && pwd -P)
-WPT_ROOT=$SCRIPT_DIR/../..
-cd $WPT_ROOT
-
-mkdir -p ~/meta
-
-python tools/ci/tag_master.py
-./wpt manifest -p ~/meta/MANIFEST.json
-cp ~/meta/MANIFEST.json $WPT_MANIFEST_FILE
-# Force overwrite of any existing file
-gzip -f $WPT_MANIFEST_FILE
diff --git a/tools/ci/tag_master.py b/tools/ci/manifest_build.py
similarity index 79%
rename from tools/ci/tag_master.py
rename to tools/ci/manifest_build.py
index d672d13fe2..43cfb55f20 100644
--- a/tools/ci/tag_master.py
+++ b/tools/ci/manifest_build.py
@@ -1,6 +1,7 @@
 import json
 import logging
 import os
+import subprocess
 import sys
 
 import requests
@@ -17,6 +18,32 @@
 logger = logging.getLogger(__name__)
 
 
+class Status(object):
+    SUCCESS = 0
+    FAIL = 1
+    NEUTRAL = 78
+
+
+def run(cmd, return_stdout=False, **kwargs):
+    print(" ".join(cmd))
+    if return_stdout:
+        f = subprocess.check_output
+    else:
+        f = subprocess.check_call
+    return f(cmd, **kwargs)
+
+
+def create_manifest(path):
+    run(["./wpt", "manifest", "-p", path])
+
+
+def compress_manifest(path):
+    for args in [["gzip", "-k", "-f", "--best"],
+                 ["bzip2", "-k", "-f", "--best"],
+                 ["zstd", "-k", "-f", "--ultra", "-22"]]:
+        run(args + [path])
+
+
 def request(url, desc, data=None, json_data=None, params=None, headers=None):
     github_token = os.environ.get("GITHUB_TOKEN")
     default_headers = {
@@ -92,7 +119,7 @@ def tag(owner, repo, sha, tag):
     return True
 
 
-def create_release(owner, repo, sha, tag, summary, body):
+def create_release(manifest_path, owner, repo, sha, tag, summary, body):
     if body:
         body = "%s\n%s" % (summary, body)
     else:
@@ -117,7 +144,7 @@ def create_release(owner, repo, sha, tag, summary, body):
         params = {"name": upload_filename,
                   "label": "MANIFEST.json%s" % upload_ext}
 
-        with open(os.path.expanduser("~/meta/MANIFEST.json%s" % upload_ext), "rb") as f:
+        with open("%s%s" % (manifest_path, upload_ext), "rb") as f:
             upload_data = f.read()
 
         logger.info("Uploading %s bytes" % len(upload_data))
@@ -148,7 +175,7 @@ def main():
     repo_key = "GITHUB_REPOSITORY"
 
     if not should_run_action():
-        return
+        return Status.NEUTRAL
 
     owner, repo = os.environ[repo_key].split("/", 1)
 
@@ -162,16 +189,28 @@ def main():
     else:
         tag_name = "merge_pr_%s" % pr
 
+    manifest_path = os.path.expanduser(os.path.join("~", "meta", "MANIFEST.json"))
+
+    os.makedirs(os.path.dirname(manifest_path))
+
+    create_manifest(manifest_path)
+
+    compress_manifest(manifest_path)
+
     tagged = tag(owner, repo, head_rev, tag_name)
     if not tagged:
-        sys.exit(1)
+        return Status.FAIL
 
     summary = git("show", "--no-patch", '--format="%s"', "HEAD")
     body = git("show", "--no-patch", '--format="%b"', "HEAD")
 
-    if not create_release(owner, repo, head_rev, tag_name, summary, body):
-        sys.exit(1)
+    if not create_release(manifest_path, owner, repo, head_rev, tag_name, summary, body):
+        return Status.FAIL
+
+    return Status.SUCCESS
 
 
 if __name__ == "__main__":
-    main()
+    code = main()
+    assert isinstance(code, int)
+    sys.exit(code)