diff --git a/make_wheels.py b/make_wheels.py
index 3330659..bacfd75 100644
--- a/make_wheels.py
+++ b/make_wheels.py
@@ -48,7 +48,7 @@ def writestr(self, zinfo_or_arcname, data, *args, **kwargs):
 
 def make_message(headers, payload=None):
     msg = EmailMessage()
-    for name, value in headers.items():
+    for name, value in headers:
         if isinstance(value, list):
             for value_part in value:
                 msg[name] = value_part
@@ -71,18 +71,18 @@ def write_wheel(out_dir, *, name, version, tag, metadata, description, contents)
     dist_info  = f'{name}-{version}.dist-info'
     return write_wheel_file(os.path.join(out_dir, wheel_name), {
         **contents,
-        f'{dist_info}/METADATA': make_message({
-            'Metadata-Version': '2.1',
-            'Name': name,
-            'Version': version,
-            **metadata,
-        }, description),
-        f'{dist_info}/WHEEL': make_message({
-            'Wheel-Version': '1.0',
-            'Generator': 'ziglang make_wheels.py',
-            'Root-Is-Purelib': 'false',
-            'Tag': tag,
-        }),
+        f'{dist_info}/METADATA': make_message([
+            ('Metadata-Version', '2.4'),
+            ('Name', name),
+            ('Version', version),
+            *metadata,
+        ], description),
+        f'{dist_info}/WHEEL': make_message([
+            ('Wheel-Version', '1.0'),
+            ('Generator', 'ziglang make_wheels.py'),
+            ('Root-Is-Purelib', 'false'),
+            ('Tag', tag),
+        ]),
     })
 
 
@@ -134,20 +134,33 @@ def write_ziglang_wheel(out_dir, *, version, platform, archive):
         name='ziglang',
         version=version,
         tag=f'py3-none-{platform}',
-        metadata={
-            'Summary': 'Zig is a general-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.',
-            'Description-Content-Type': 'text/markdown',
-            'License': 'MIT',
-            'Classifier': [
-                'License :: OSI Approved :: MIT License',
-            ],
-            'Project-URL': [
-                'Homepage, https://ziglang.org',
-                'Source Code, https://github.com/ziglang/zig-pypi',
-                'Bug Tracker, https://github.com/ziglang/zig-pypi/issues',
-            ],
-            'Requires-Python': '~=3.5',
-        },
+        metadata=[
+            ('Summary', 'Zig is a general-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.'),
+            ('Description-Content-Type', "'text/markdown'; charset=UTF-8; variant=GFM"),
+            ('License-Expression', 'MIT'),
+            ('License-File', 'LICENSE'),
+            ('License-File', 'ziglang/lib/libc/glibc/LICENSES'),
+            ('License-File', 'ziglang/lib/libc/mingw/COPYING'),
+            ('License-File', 'ziglang/lib/libc/musl/COPYRIGHT'),
+            ('License-File', 'ziglang/lib/libc/wasi/LICENSE'),
+            ('License-File', 'ziglang/lib/libc/wasi/LICENSE-APACHE'),
+            ('License-File', 'ziglang/lib/libc/wasi/LICENSE-APACHE-LLVM'),
+            ('License-File', 'ziglang/lib/libc/wasi/LICENSE-MIT'),
+            ('License-File', 'ziglang/lib/libcxx/LICENSE.TXT'),
+            ('License-File', 'ziglang/lib/libcxxabi/LICENSE.TXT'),
+            ('License-File', 'ziglang/lib/libunwind/LICENSE.TXT'),
+            ('Classifier', 'Development Status :: 4 - Beta'),
+            ('Classifier', 'Intended Audience :: Developers'),
+            ('Classifier', 'Topic :: Software Development :: Compilers'),
+            ('Classifier', 'Topic :: Software Development :: Code Generators'),
+            ('Classifier', 'Topic :: Software Development :: Build Tools'),
+            ('Classifier', 'Programming Language :: Other'),
+            ('Classifier', 'Programming Language :: Other Scripting Engines'),
+            ('Project-URL', 'Homepage, https://ziglang.org'),
+            ('Project-URL', 'Source Code, https://github.com/ziglang/zig-pypi'),
+            ('Project-URL', 'Bug Tracker, https://github.com/ziglang/zig-pypi/issues'),
+            ('Requires-Python', '~=3.5'),
+        ],
         description=description,
         contents=contents,
     )