diff --git a/CHANGELOG.md b/CHANGELOG.md
index bf3385992..155f44e99 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Request locally compiled Python runtimes through `BUILDCURL_URL` instead of the hosted Barebuild SSH compiler.
+- Default to `https://buildcurl.com` when no local compiler URL is provided, preserving compatibility with released pkgr actions.
 
 ## v221 (2022-10-12)
 
diff --git a/bin/download-python-runtime b/bin/download-python-runtime
index 4dd32cfc3..4d9db50c2 100755
--- a/bin/download-python-runtime
+++ b/bin/download-python-runtime
@@ -5,10 +5,10 @@ runtime="${1:?runtime is required}"
 destination="${2:?destination is required}"
 prefix="${3:?prefix is required}"
 
-: "${BUILDCURL_URL:?BUILDCURL_URL is required}"
+buildcurl_url="${BUILDCURL_URL:-https://buildcurl.com}"
 
 curl --get --fail --location --silent --show-error \
-  "$BUILDCURL_URL" \
+  "$buildcurl_url" \
   --data-urlencode "recipe=python" \
   --data-urlencode "version=${runtime#python-}" \
   --data-urlencode "target=$(cat /etc/version)" \
diff --git a/spec/local_buildcurl_spec.rb b/spec/local_buildcurl_spec.rb
index 840c17547..35d659efc 100644
--- a/spec/local_buildcurl_spec.rb
+++ b/spec/local_buildcurl_spec.rb
@@ -59,17 +59,49 @@
     end
   end
 
-  it 'fails without BUILDCURL_URL' do
-    _stdout, stderr, status = Open3.capture3(
-      { 'BUILDCURL_URL' => nil },
-      downloader,
-      'python-3.10.8',
-      Dir.tmpdir,
-      '/app/.heroku/python'
-    )
+  it 'uses the hosted compiler when BUILDCURL_URL is not set' do
+    Dir.mktmpdir do |directory|
+      fake_bin = File.join(directory, 'bin')
+      source = File.join(directory, 'source')
+      destination = File.join(directory, 'destination')
+      archive = File.join(directory, 'runtime.tgz')
+      arguments = File.join(directory, 'curl-arguments')
+      FileUtils.mkdir_p([fake_bin, source, destination])
+      File.write(File.join(source, 'python'), 'hosted runtime')
+      system('tar', 'czf', archive, '-C', source, '.', exception: true)
 
-    expect(status).not_to be_success
-    expect(stderr).to include('BUILDCURL_URL is required')
+      File.write(File.join(fake_bin, 'curl'), <<~SH)
+        #!/usr/bin/env bash
+        printf '%s\n' "$@" > "$CURL_ARGUMENTS"
+        /bin/cat "$CURL_ARCHIVE"
+      SH
+      File.write(File.join(fake_bin, 'cat'), <<~SH)
+        #!/usr/bin/env bash
+        if [[ "$1" == "/etc/version" ]]; then
+          echo ubuntu:24.04
+        else
+          exec /bin/cat "$@"
+        fi
+      SH
+      FileUtils.chmod(0o755, [File.join(fake_bin, 'curl'), File.join(fake_bin, 'cat')])
+
+      _stdout, stderr, status = Open3.capture3(
+        {
+          'BUILDCURL_URL' => nil,
+          'CURL_ARGUMENTS' => arguments,
+          'CURL_ARCHIVE' => archive,
+          'PATH' => "#{fake_bin}:#{ENV.fetch('PATH')}"
+        },
+        downloader,
+        'python-3.10.8',
+        destination,
+        '/app/.heroku/python'
+      )
+
+      expect(status).to be_success, stderr
+      expect(File.read(File.join(destination, 'python'))).to eq('hosted runtime')
+      expect(File.readlines(arguments, chomp: true)).to include('https://buildcurl.com')
+    end
   end
 
   it 'propagates download failures without retrying' do