diff --git a/tests/test_metadata.py b/tests/test_metadata.py
index 34214302..78fe40db 100644
--- a/tests/test_metadata.py
+++ b/tests/test_metadata.py
@@ -9,6 +9,7 @@ def test_pkginfo_to_metadata(tmpdir):
         ('Provides-Extra', 'test'),
         ('Provides-Extra', 'signatures'),
         ('Provides-Extra', 'faster-signatures'),
+        ('Requires-Dist', "pip @ https://github.com/pypa/pip/archive/1.3.1.zip"),
         ('Requires-Dist', "ed25519ll; extra == 'faster-signatures'"),
         ('Requires-Dist', "keyring; extra == 'signatures'"),
         ('Requires-Dist', "keyrings.alt; extra == 'signatures'"),
@@ -28,6 +29,8 @@ def test_pkginfo_to_metadata(tmpdir):
 
     egg_info_dir = tmpdir.ensure_dir('test.egg-info')
     egg_info_dir.join('requires.txt').write("""\
+pip@https://github.com/pypa/pip/archive/1.3.1.zip
+
 [faster-signatures]
 ed25519ll
 
diff --git a/wheel/metadata.py b/wheel/metadata.py
index 4fa17cde..c6a37364 100644
--- a/wheel/metadata.py
+++ b/wheel/metadata.py
@@ -16,7 +16,10 @@
 
 
 def requires_to_requires_dist(requirement):
-    """Compose the version predicates for requirement in PEP 345 fashion."""
+    """Return the version specifier for a requirement in PEP 345/566 fashion."""
+    if requirement.url:
+        return " @ " + requirement.url
+
     requires_dist = []
     for op, ver in requirement.specs:
         requires_dist.append(op + ver)